The Japanese occupation of West Sumatra, officially known as Sumatora Nishi Kaigan Shū (Japanese: スマトラ西海岸州, Hepburn: Sumatora Nishikaigan-shū, lit. 'West Coast Province of Sumatra'), started from 1942 until 1945 when the region was controlled by the Empire of Japan. The occupation was notable and recognized as one of the rare instances where a civilian government was established, rather than being governed by someone associated with the Japanese Imperial Army. The Japanese entered Padang on 17 March 1942 and within ten days all important cities in the West Sumatra region were occupied without resistance from the Dutch. The Japanese occupation of the region ended on 17 August 1945 with the proclamation of Indonesian independence by Sukarno and Mohammad Hatta.

In the early days of the Japanese occupation, events in Padang were heavily influenced by Sukarno. In October 1943, Japan ordered the establishment of the Giyūgun to help with defence. Led by Chatib Sulaiman, the Giyūgun was the only army unit formed by the Japanese in West Sumatra. This voluntary army would later become the backbone of Indonesia's armed forces after independence.

In December 1941, the Japanese 14th Army, under the command of Admiral Kondo, successfully defeated U.S. military forces on Luzon Island, facilitating the Japanese occupation of the Philippines. Concurrently, the Imperial Japanese Navy, in cooperation with the Japanese 25th Army for intelligence sharing, sank the British battleships Prince of Wales and Repulse in Singaporean waters on December 10, 1941. The defeat of the British naval forces significantly weakened British defenses and morale in the region, enabling Japanese forces to advance on British-controlled Malaya with relative ease, with much of the British Pacific Fleet unreinforced until March 1942 and withdrawn to Ceylon and scattered across the Dutch East Indies. Following these operations, the 16th Army, led by Lieutenant General Hitoshi Imamura, and the 25th Army, under the command of General Yamashita Tomoyuki, began their sights to take control of Indonesia.

From its intelligence reports, the Netherlands was well aware of Japan's intention to expand its influence to Indonesia. Therefore, the Dutch tried to organize a limited militia, including education such as the Military Academy in Breda and the formation of Vaandrigs. Dutch Foreign Minister, Eelco van Kleffens, came to Batavia under the Dutch government-in-exile at the beginning of 1942 and told that the Dutch East Indies, with the help of the people, was ready to face the Japanese. The Dutch however did not foresee the lack of support from the local population.

In January 1942, there were notably two Japanese flying boat attacks on the city of Padang. The first attack was carried out by a flying boat by dropping only one bomb in front of Padang station, near the railroad workshops. This was the first bombing to ever occur in West Sumatra. The second attack in January was also launched by seven Japanese flying boats over the port of Emmahaven. After a few circles over the city of Padang, the flying boats dropped bombs on ships at anchor in the docks and warehouses were also targeted. As a result, about three large ships were sunk, parts of the warehouses and wharves were burned, and the bridge for loading coal onto ships was damaged.

In February 1942, the Japanese began its invasion of Sumatra by deploying paratroop units in Palembang. Preparing for war against the enemy, the Dutch, were busy organizing exercises such as the Stadswacht, Landswacht, Luchtbeschermingsdienst (LBD), and preparations for militia duties. However such preparations were insufficient when the Japanese arrived. According to Audrey Kahin, the Japanese intended to preempt Dutch plans to damage oil installations near Palembang. From Palembang, the Japanese army soon spread across southern and northern Sumatra swiftly. By mid-March, larger numbers of troops landed on the northern and eastern coasts of Sumatra, moving rapidly southwards.

Through the Agreement of Kalijati on 8 March 1942, the Dutch ceded the Indonesian colonies to Japan. After the occupation began, the Japanese divided Indonesia into three military administration areas. The Sumatra region was under the 25th Army Military Government Department (Rikugun) in Singapore led by General Tomoyuki Yamashita. However, for nine days after receiving the Dutch surrender, Japan had not yet reached West Sumatra, leaving a power vacuum in the region and what remained of Dutch authority in complete disarray. Many high-ranking Dutch officials had fled to safety on allied ships or evac planes, abandoning those who remained behind and creating mass panic. Most of the Dutch residents who stayed in West Sumatra lived in small houses or military pensions, while only a few Dutch military police patrolled the area. Even after the official capitulation of the Dutch East Indies, rogue elements of the KNIL army of Sumatra disavowed this order. Led by then Governor of Sumatra and former resident of Sumatra's West Coast, Adriaan Isaac Spits, he declared the Dutch army in Sumatra would continue to fight "to the last drop of blood." He and rebelling KNIL generals later formed the Dutch Territorial Command in Sumatra. At that time, the Territorial Command of Central Sumatra, including West Sumatra and North Sumatra, was led by Major General Roelof T. Overakker, taking over Lt. Col. John Blogg's military jurisdiction over West Coast Sumatra. The Dutch planned to build defenses in the mountainous areas of Aceh, in the districts of Takengon, Tanah Luos, and Tanah Alas. The Dutch Territorial Command in Sumatra then enacted a scorched earth policy across West Sumatra to slow down the Japanese advance, much to the suffering of the locals.

The Japanese army's advance from the north through Lubuk Sikaping encountered little to no resistance from the remnants of the Dutch East Indies army. Only the advance from the east met some resistance, but it to was also negligible. As the Dutch forces retreated, they attempted to sabotage their own infrastructure and resources to prevent them from falling into Japanese hands. Initially, the Dutch Territorial Command called on the local population in West Sumatra to destroy key infrastructure that could potentially be used by the Japanese upon their arrival. However, this request was rejected by the people, as they were unwilling to damage their own region. Realizing that the Dutch were without local support, the Dutch forces grew increasingly panicked. Compounded by the approach of the Japanese army, and the realization that they could not rely on assistance from the local population, leaving them in a precarious situation, as if confronting two adversaries—an external military threat and the increasing internal discontent from the people of West Sumatra. The Dutch army retreated by first damaging the Pulau-Musang Bridge in the Jambi area. Before surrendering power, the Dutch had dumped all their supplies of oil, gasoline, and various alcoholic beverages into the river (flood canal) near Sawahan in Padang, which resulted in fires along the river, reaching the Jati area and the villages of Terandam and Ranah. These fires fortunately did not cause significant damage. A similar act of sabotage occurred near Bukittinggi in Gadut, where the Dutch set fire to their fuel supplies, filling the air with thick black smoke. In other towns such as Batusangkar, Payakumbuh, and Solok, the Dutch burned gasoline and kerosene stored in depots owned by the Bataafse Petroleum Maatschappij (BPM). However, through the initiative of Indonesian employees working at the depots, a large part of the kerosene stored in cans was also saved and distributed to the people. Likewise, groups of people were able to salvage a large number of abandoned drums containing gasoline and lubricating oil, so that they could be used for public transport, which had been in short supply.

As the Dutch troops began to withdraw from West Sumatra and Tapanuli, they maintained the appearance of a force still willing to resist the Japanese advance. The rugged terrain of West Sumatra, with its mountainous landscape, valleys, and canyons, was initially planned by the Dutch as a potential last line of defense. If push came to shove, then West Sumatra would be burned to the ground, leaving the enemy with nothing but rubble. The people of Minangkabau, with few fully knowing the impending Japanese invasion, sense that something was awry among the Dutch and felt that disaster might happen. Aware of the losses that the scorched earth tactic could cause, many were strongly against it. Even former Indonesian East Indies officials who worked in the Dutch local government voiced disapproval. Demonstrations were planned to happen on 12 March on Padang Panjang against the scorched policy. Led by Chatib Suleiman, Leon Salim, and several supporters, they established the Komite Penegak Merah Putih (Committee to Uphold the Red and White) and planned to raise the Indonesian flag at Padang Panjang due to its perceived symbolism. They intend to demand the Dutch to hand over power to the Indonesians before the Japanese army enters West Sumatra, so they will be the ones to negotiate with the Japanese occupation army. They were later arrested after word spread about the planned protests and were subsequently taken by the Dutch to the mountains of West Sumatra where the Dutch intended to make a final stand against the Japanese. Historian Martamin believed that by bringing high-ranking political prisoners such as Chatib Sulaiman, the Dutch hoped to secure their safety from local discontent during their retreat to the mountains. At that time, Chatib Sulaiman had significant influence over the people of West Sumatra, especially among the Pemuda. The Dutch were also aware of efforts centered in Padang Panjang aimed at local resistance, but due to Chatib Sulaiman's involvement, they were able to retreat safely. The Dutch retreat to Kutacane, carried out in haste and panic, severely damaged their dignity and what's left of the reputation hold within the governance of the Dutch Territorial Command in the eyes of the people. Later pressure from the Japanese, mainly from bombing campaigns, led the Dutch to instead change locations to Setan Mountain in Atceh. Originally sentenced to death, the political prisoners were all freed once the Japanese occupied the town of Kutacane without resistance. They all went back to West Sumatra once they got permission from the occupying Japanese. Previously, Sukarno had convinced Japanese occupational forces to send several of their men to scout and find Chatib Suleiman and his group who were kidnaped by the Dutch. They later arrived in Padang Panjang and then escorted to Bukittinggi on 2 April 1942.

The Japanese entry into West Sumatra almost coincided with their movements in other parts of Sumatra. Japanese army soldiers entered Padang City on 17 March 1942. Within days, all of West Sumatra was under their control and the Dutch military commander in Sumatra surrendered unconditionally to the Japanese.

To academic Audrey Kahin, one of the focuses of the Japanese occupation army during the first year of occupation was to get the government apparatus in Sumatra functioning so that they could make efficient use of its vital resources, particularly the oil fields near Palembang and the rubber plantations in East Sumatra. Within the broader Japanese framework, West Sumatra was not initially a priority in terms of economic interests, but it held significant strategic importance. Initially, it was a major route through which the Japanese expected to infiltrate their agents into Sumatra. However, since mid-1943, Sumatra's strategic importance increased as the Japanese predicted that Allied counterattacks against the west coast of Sumatra and surrounding islands would be launched via the Andaman and Nicobar Islands. The Japanese revived the Dutch system of government and reappointed most of the former Indonesian officials who had been in the previous bureaucracy. The Japanese divided Sumatra into 10 shū (identical to the administrative regions of the Dutch residencies and the former province system of Japan), each headed by a shūchōkan.

Sumatra in the occupation government structure was initially under the control of the Singapore-based 25th Army. However, the 25th Army Command concluded that it was not possible to govern Sumatra from its headquarters in Singapore, especially in terms of protecting the area around vital installations. In subsequent developments, the direction of the war since the beginning of 1943 was unfavorable for the Japanese. On various Pacific fronts, the Japanese army began to be pushed back and the initiative for the attack lay with the Allies. This circumstance had forced the Japanese Army Command for the “Southern Area” to shift its main focus of policy from consolidating power in the newly occupied areas to a defensive strategy against possible Allied counterattacks. After a feud between Yaheita Saito and Shigenori Kuroda, Chief of Staff of the Southern Army, over the issue of relocating the 25th Army to Sumatra, the headquarters of the 25th Army was moved from Singapore to Bukittinggi in Sumatra in May 1943. Consequently, Sumatra, which had previously been attached to Malaya, was made a self-governing unit. Recognizing Sumatra's potential to support the Japanese economy and military in the face of Allied forces, the Japanese separated Sumatra from Malaya on 1 May 1943. The 25th army took direct control of the city, later renaming it from Stadsgemeente Fort de Kock to Bukittinggi-Si Yaku Sho (or simply Shiyakusho, lit. 'Municipal office; council; city hall') and expanded the city limits for their needs. The city was selected as the headquarters of the 25th Army due to its strategic and isolated location. Its hilly topography, flanked by towering mountains and valleys, most notably Sianok Canyon, offered natural defense advantages, making it an ideal base for military operations during the Japanese occupation.

In the first months of the Japanese occupation, Colonel Fujiyama and his Assistant I. Wakamatsu, who were responsible for forming the ranks of the government in West Sumatra, relied on the advice of a local official, Dt. Madjo Urang, in appointing new officials. Previously, after the 1927 Rebellion, Achmad Arief Dt. Madjo Orang was appointed assistant demang for adat affairs, then became demang for adat affairs in 1940. In mid-1943, the Commander of the 25th Army, Tomoyuki Yamashita, succeeded in establishing the Gunseikanbu, the central military government staff as the executive organ of government in Sumatra. This central military government staff was headed by a Gunseikan who was directly held by the Commander of the 25th Army. In carrying out his administration, the gunseikan formed ten departments headed by a director. The ten departments were the Department of the Interior, the Department of Police, the Department of Justice, the Department of Industry, the Department of Finance, the Department of Public Works, the Department of Transport, the Department of Information, the Transfer and Shipping Department, and the Department of Meteorology. These ten directors were overseen by the Director of the Interior who acted as the Deputy Gunseikan. Meanwhile, each Shū (州) government had three departments, namely the Department of the Interior, the Police Department, and the Social Welfare Department.

The 25th Army had hardly any close relationship with the 16th Army in Java, let alone the Imperial Japanese Navy in Eastern Indonesia, attributed to the historical interservice rivalry between the Imperial Japanese Army and the Imperial Japanese Navy. Consequently, this contributed to Sukarno's extended stay in West Sumatra, as well as the 25th Army's reluctance to relinquish control over Malaya during Yaheita Saito's tenure. Thus it comes to no surprise that when Tokyo promised independence for Indonesia, including all of the former Dutch East Indies, through the Koiso Declaration on 7 September 1944, the 25th Army Command in Bukittinggi strongly opposed the inclusion of Sumatra within the promised Indonesian territory. The 25th Army had tried to hold on to the territory until the end of the Japanese occupation, with one by a temporary measure by preparing a Sumatra-wide Chūō Sangiin (Central Advisory Council) intended to rival that of the 16th Army's Chūō Sangiin in Java, chaired by Sukarno. The Sumatran Chūō Sangiin held its first session in May 1945, chaired by Mohammad Sjafei and Chatib Suleiman as its secretary. The council's potential role in shaping Sumatra's future was effectively curtailed, not only by the restrictions imposed by the 25th Army Command but also by the region's historical developments in preceding years. According to historian Audrey Kahin, a significant factor contributing to the declination of Sumatra's self-determination plan nudged by the 25th Army since the beginning of the Japanese occupation was the minimal contact between provinces (Shū) and that it was only at the shū level that indigenous organizations can sincerely began to emerge.

The West Coast Sumatra Province was formed in August 1942 under the name Sumatora Nishi Kaigan Shū to replace the residency system to the Shū (州) system. The province has its capital in Padang. Former Toyama Prefecture Governor Yano Kenzo served as the first shūchōkan. As tasked for being the civilian leader for the West Coast Sumatra Province, Yano Kenzo arrived in Padang on 9 August 1942 along with 68 civil servants. The division of West Coast Sumatra's administrative units was almost entirely based on the division made by the Dutch in 1935, consisting of 5 afdeelingen, 19 onderafdeelingen, 20 districts, 49 onderdistricts, and at least 430 nagari. Historian Gusti Asnan noted that a slight difference from the division of administrative units by the Japanese was the exclusion of Fuku Bun Bangkinang and the inclusion of the Kampar Regency in Rio Shū (Riau Province). In running the wheels of government in West Coast Sumatra, the Japanese did not make many changes to the government structure, except for changes in nomenclature into Japanese. The Afdeeling, headed by an assistant resident, was changed into a bunshū (分周), headed by a bunshūchō (分周長). The onderafdeeling headed by a controller was changed to a fuku bunshū headed by a fuku bunshūchō. The district headed by a demang was changed to a gun (郡) headed by a gunchō. Onderdistricts headed by assistant demangs were transformed into fukugun headed by a fuku gunchō. Except for important positions in the administration, the Japanese still used native officials who had previously been in the Dutch East Indies administration on condition that they did not infringe on Japanese authority. This was because the Japanese who first came were soldiers who did not understand the organization and intricacies of civil governance. Japanese reports in 1942 indicate that the government apparatus for West Sumatra who were later sent had never arrived to Indonesia due to the ship being hit and sunk by Allied torpedoes. The highest native official headed the gun and its subordinate structure, the fukugun (副郡). The smallest government unit, the nagari, was termed son and the head of the nagari was called sonchō or son (村).

The Japanese made sure that cooperation with the natives in Sumatra was vital for the war effort, given the resources Sumatra holds. And so, the Japanese sought cooperation among the native elite, both from civil servants (known as the pamong praja) and prominent leaders in the guise of independence, rousing support from the locals. Japan's attitude towards the leaders of West Sumatra society was described by H.J. Benda in Document No. 47, dated April 27, 1942. The occupation government recognized the importance of acknowledging sources of political power in West Sumatra. Nationalist figures from the region had to be embraced, and political leaders, as well as other influential figures within the community, were co-opted to help achieve the goal of “Japanizing” the people of West Sumatra. Through prominent local leaders like Moh. Syafei, Chatib Sulaiman, and others, the Japanese sought to erase Western influence and instill a deep hatred for anything associated with Western culture. Slogans created by the Japanese, such as "Inggeris dilinggis" (the British will be crushed), "Amerika diseterika" (America will be ironed out), and "Belanda kurang-ajar" (the Dutch are insolent), were used as propaganda tools to foster anti-Western sentiment among the people of West Sumatra. The Pamong praja were useful for keeping the administrative system running, which basically followed the pattern from the Dutch colonial period. In reality, however, the policies of the military leaders in Sumatra were largely constrained by the principles governing the administration of the occupied "southern territories", which dictated that the native pribumi population should be "guided in such a way as to engender confidence in imperial power, and premature encouragement of native independence movements should be prevented".

At early morning, led by Colonel Fujiyama, the first Japanese soldiers silently entered the city of Padang on 17 March 1942, and ten days later the Dutch military commander in Sumatra surrendered unconditionally. Historian Gusti Asnan notes that Japanese spies under the F-Kikan, had previously exercised influence over the Minangkabau people. Some of the Japanese who had settled in West Sumatra since the 1920s acted as Japanese intelligence "sent to pave the way for their occupation." The Japanese military was then sent to Sumatra to propagandize the victory of the Japanese forces in the war, their intention to "liberate the people", and their hope for cooperation in preventing the destruction of oil-related facilities and infrastructure by the Dutch and Indies authorities. These efforts were particularly successful in Atceh, Northern Sumatra, and West Coast Sumatra, where uprisings and actions to prevent the destruction of facilities by local residents were seen in various areas in time for the Japanese military advance.

When the locals of Padang ventured out early morning, well-armed Japanese troops were seen on the streets of Padang, occupying strategic locations. Some were on foot, while others were on bicycles. Initially, there was no display of fear; many even greeted the soldiers with gratitude. Shortly thereafter, the city saw an influx of people from neighboring areas who wanted to observe the newly arrived Japanese troops. The arrival of the Japanese army in Padang was initially hailed by the people, who chanted "Merdeka! Banzai! Long live Japan!" The people had been convinced that the Japanese were coming to liberate the nation from the rule of Western Imperialism. The Japanese invoked the slogan of Asia for Asians as a liberator of Asia from imperialism. However, the situation soon changed, and tensions increased as the soldiers began to arrest people and confiscate bicycles. Anyone who attempted to resist was met with physical force. Consequently, people started hiding possessions that might attract a soldiers' attention. Watching how the soldiers act, many began to have the courage to rob the contents of Dutch and Chinese houses in remote isolated events. This later spiraled uncontrollably into forming a "bumi angkat" movement across the region, with many justifying their act as revenge. Dutch residences were ransacked and looted, and violence, including murder, became inevitable. The Chinese community, which had been seen as favored by the Dutch, became another target for the people's wrath. In every city in West Sumatra, the Chinese quarters, which were both residential and commercial hubs, were attacked, as few Dutch remained in the area. Chinese shops were looted and destroyed, and in some cases, killings occurred. The term "Cina Mengamuk" emerged during this time, as the Chinese community retaliated in an attempt to defend themselves against the attacks.

The Japanese tried to regain control of the situation left by the ungoverned power vacuum left by the Dutch in Padang, with days later public executions were announced in the beaches of Kasiek-Angek in Padang. The one of the first to be publicly executed was a person named Bambang Ateh. He first dug his own grave and sat on his knees against the sea to be shot from behind. This event later stopped the many robberies and the "Bumi angkat" movement altogether. Along the coastline of Padang Beach there are still unmarked burial sites.

Initially exiled to Bengkulu for his disruptive political activities, Sukarno was marched, bussed, and trucked to Padang with the intention of transporting him to Australia to be kept as a prisoner. When word spread about the impending Japanese landings in Padang, the Dutch abandoned Sukarno to save themselves. Dutch resistance eventually collapsed across West Sumatra as reports of Japanese landings arrived not only in Padang, West Sumatra, but also across the East Indies archipelago. After the Dutch failed to take Sukarno to Australia, he was stuck in West Sumatra for a period of three to five months, from February 1942 to July 1942. Hizbul Wathan members, an Islamic scouts association associated with Muhammadiyah at the time based out of Ganting, went to retrieve Sukarno and bring him to Padang by cart, later being held under the protection of the local Japanese garrisons stationed in the cities and villages of Sumatra. Initially, the Japanese had files on Sukarno and decided that his return to Java was necessary to stabilize Indonesia. This decision was explicitly made and arranged by the Japanese 16th Army Headquarters after receiving numerous letters from Indonesian youths and student groups requesting the Army to find Sukarno and allow him to return to Java. However, during the first months of occupation, the Military Administration had no clue about his whereabouts, prolonging his stay in West Sumatra. In an attempt to locate Sukarno, the commander of the Japanese army in the city of Padang, Major Itoh, asked a liaison named Jahja Djalil to deliver Captain Sakaguchi to Sukarno. Jahja Djalil had previously established contacts with the Japanese Consulate in Batavia on behalf of the Harian Persamaan newspaper in Padang as tensions rose in the Pacific.

From word of mouth, it was later found that, in Padang, Sukarno and his first wife, Inggit Garnasih, stayed at a halfway house owned by Dr. Waworuntu, a veterinarian and friend of Sukarno. It was from this house that Sukarno resumed his activities as a leader of the struggle. He was always available, not only for political or matters of the homeland but also for simple gatherings, often accepting meal invitations from the public. Free and unrestricted from the confines of Dutch oversight, Sukarno's popularity continued to grow, as his speeches inspired people and strengthened their resolve to face the challenges ahead. During his travels, he was frequently accompanied by Sutan Usman Karim, also known as Suska, who at times served as his chauffeur in Padang and at other times acted as his spokesperson. The historic house was destroyed in 2023 to make way for a restaurant.

Captain Sakaguchi was the first to introduce himself at the meeting, presenting his official identification card as a member of the Sendenbu (宣伝部, Propaganda Department). He was accompanied on this visit to Sukarno by Jahja Djalil as his translator. In response to Sukarno's inquiry about the purpose of his visit, Captain Sakaguchi stated, “It is nothing. I know that I need to make your acquaintance, and that is why I have come. That is all. I did not come to give orders to you. Meeting the famous Mr. Sukarno is my first duty. We know everything about you. We know you are the leader of Indonesia and an influential person. It is our honor to give you the respect you deserve.” Days after the first contact, a second delegation were represented by Colonel Fujiyama of the Imperial Army for Sumatra and commander of the F-Kikan movement in Sumatra, a military intelligence operation that infiltrated Sumatra before the fall of the Netherlands. During the two hour meeting, Colonel Fujiyama had assured Sukarno that Japan would not interfere with Indonesia's national interests, recognizing the diverse religious and cultural makeup of the Indonesian people. His main objective was to restore peace and manage the government in the region efficiently. In return, Fujiyama promised formal and active political cooperation. Under severe psychological pressure from the sudden intrusion, Sukarno, in response against his will, agreed to collaborate with Japan, stating his intention to carry out propaganda aligned with Indonesia's goals while also working towards the nation's independence. And so along the course of the occupation in Indonesia, Sukarno showed a cooperative attitude towards the Japanese. However, the leaders and figureheads of the National Party of Indonesia (PNI) were divided during a meeting at the Bumiputra office in Bukittinggi. Some supported cooperation with the Japanese, while others refused to do so. Anwar Sutan Saidi, the head of the pro-independence bank, Bank National, and various trade organizations, chose to avoid the political track that were of the result of Japanese collaboration and instead focus on the economic track. His aim was to raise funds and procure weapons to support the struggle for independence. Tamimi Usman led a group of people who followed Sutan Syahrir's non-cooperative way and mobilised underground activities. The group led by Chatib Sulaiman followed the path of struggle for independence of Indonesia rather than collaborating with the Japanese to gain it.

In West Sumatra, Sukarno managed to persuade most independence movement leaders to cooperate with Japan. Intending to create an independence committee, Sukarno decided to stay in Padang in February 1942 for 15 days. In his speech in Padang, Sukarno urged the people not to resist the Japanese army because the forces were not equal. According to Sukarno, the Indonesian people must use Japan to achieve their goal of realising Indonesian independence. Through his cooperative attitude, Sukarno managed to prevent the Japanese army's harsh actions against the people of West Sumatra. The Japanese occupational army slowly realizing his popularity as becoming more to gain for being a Japanese asset. As each passing train station reaching to Bukittinggi, he was met with a hero's welcome. Sukarno persuaded most of the national figures in West Sumatra to cooperate with Japan. When the Japanese army prohibited the raising of flags other than the Japanese flag, Sukarno once asked Captain Sakaguci to cancel the order to lower the red and white flag. His request was rejected. On this issue, Sakaguchi warned, "Perhaps, Mr Soekarno, you should not delay this too much." Sukarno followed otherwise and before carrying out this very heavy instruction, Sukarno went to the mosque to pray. He then ordered the people to lower the flag "until the time comes when we can fly Sang Dwi-warna freely from all forms of foreign domination." Sukarno and Hatta saw co-operation with Japan as the best way to achieve the goal of Indonesian independence, "sailing in one ship with the Japanese while carrying our own merchandise." The flag issue prohibition comes when Indonesians in Bukittinggi had been flying the Indonesian flag side by side with the Japanese flag in their perceived 'liberation'. When the occupying 25th Army ordered the Indonesian flag to be taken down, Anwar Sutan Saidi had protested and he was put in prison on 3 April 1942, later suspecting that he had pro-Dutch ties. Sukarno had to personally intervene for Anwar's release once he learned of Anwar's capture and subsequent tortures by the Kempeitai. By then Sukarno and West Sumatran leaders formed the People's Committee, as a temporary government to maintain calm in the region as Japanese troops consolidated their power. Meanwhile, Leon Salim, Chatib Suleiman, and Mohammad Nasroen united all existing youth organisations into the Pemuda Nippon Raya organization. However, this organisation did not last long as the Japanese peeked the idea behind its establishment and labeled it as a nationalist organization in disguise. Leon Salim was arrested by the Japanese on 14 November 1942 on suspicion of pretending to help them, but was released after a week. After the Pemuda Nippon Raya gaffe, Political parties and national organizations were declared banned. The Taman Siswa School program, which had long been recognized as an educational institution rooted in Indonesian nationalism and culture, was forced to change its name to Taman Nippon Raya. All meetings, publications, and listening to foreign radio broadcasts were prohibited, and even non-political organizations were banned by the Japanese. Violating any of these regulations could lead to brutal consequences, including torture by the Japanese military police, the Kempetai.

Sukarno's presence was not long in West Coast Sumatra. Prior to Sukarno's relocation to Java, Colonel Fujiyama and his assistant, I. Wakamatsu, facilitated Sukarno's safe return to Jakarta while also arranging for the repatriation of Madjid Usman, a journalist from Padang, to West Sumatra as a gesture of reciprocation for the support Sukarno received during his stay in West Sumatra. This exchange was made possible only after long negotiations which resulted to an agreement that was reached between the 16th Army, which governed Java, and the 25th Army, which held authority over Sumatra. The arrangement essentially involved a reciprocal exchange: Sukarno, who had been stranded in Minangkabau, for Madjid, who was in Java. Madjid's stature as an Indonesian figure was initially seen by the Japanese as comparable to that of Sukarno. Once found and pressured by the 16th army by June 1942, Sukarno left by land and went to Emmahaven to Tanjung Priok in Java to lead the Indonesian independence struggle.

The civil administration of West Sumatra only became effective after the arrival of Yano Kenzo to West Sumatra on 9 August 1942 as 'Governor of West Coast Sumatra'. Before serving in West Sumatra, Yano had served as Governor of Toyama Prefecture. Yano Kenzo became the only civilian leader in the Japanese-occupied areas of the Dutch East Indies, a notable exception as most of the occupied territories in the archipelago were governed by local military commanders of the Japanese Imperial Army. Gusti Asnan noted that Yano played a major role in realising good cooperation between the people of West Sumatra and the Japanese. Yano opposed many policies of the 25th Army Command, but maintained friendly relations with 25th Army Commander Moritake Tanabe in Bukittinggi. Tanabe assumed that the population of Sumatra, due to its heterogeneous nature, would not be able to establish local organizations in the same way as the 16th Army had facilitated in Java, where the majority of the population was ethnically Javanese. This assumption was based on the notion that the ethnic diversity of Sumatra would hinder the formation of unified, local groups, in contrast to the more homogeneous society in Java, thus upholding the military government's administration in the early years of the occupation. Tanabe also had reservations about the increasing role of the Indonesian nationalist movement on Java, but responding to the "Koiso Promise" granting increased autonomy and eventual independence to Indonesia, which included all of the former Dutch East Indies, he established the Sumatra Central Advisory Council and trained locals for administrative leadership roles, granting political concessions to Sumatra by allowing it to form a Chūō Sangiin. However, he attempted to distance himself from local politics by as much as possible, leaving much leniency to the administration of West Coast Sumatra outside of Bukittinggi to the civilian government headed by Yano Kenzo in Padang, which acts as an administrative city for development and public works affairs in the province.

Yano Kenzo's sympathy for the local people's aspirations for independence and his disappointment with government policies, that did not match his views, were expressed in an article he wrote later in 1967. As a civilian leader, Yano Kenzo instead approached the Minangkabau people through culture and multiculturalism, rather than through force or authority much like his equivalent peers across occupied Asia. He had an interest in nature, society, and the customs of Minangkabau, which socially adhered to the matrilineal tradition. His fascination on the Minangkabau people led him on studying the culture and writing a book in February 1944. According to Gusti Asnan, his political views, which were influenced by his keen interest in Minangkabau, became the basis for his idea to initiate the establishment of several civic, social, and cultural organisations in West Sumatra. As a result, he had personally established and allowed cultural platforms and religious organisations to learn more about the country's traditions and history, such like the such as the Centre for Research on Minangkabau Society (Balai Penyelidikan Masyarakat Minangkabau) for the adat and the Minangkabau Higher Islamic Council (Majelis Islam Tinggi; MIT) for Muslim leaders of Minangkabau. For persisting in his stance against the exploitative nature of the economic policies pursued by the Japanese authorities, Yano Kenzo resigned as governor in March 1944. Officially leaving in April 1944, he was then replaced by Hattori Naoaki. The new governor, described as a "careful and cautious person," had previously served as the head of education in Sumatra. Yano argued that the Japanese occupying forces were well aware of Indonesia's abundant resources and were determined to maintain their hold on the country, even if it meant giving up the Philippines and Burma.

"...The Minangkabau of Sumatra, under my jurisdiction..., seem to be the most intelligent and economically advanced of all the tribes; and their political awareness is admirable. So, it is not surprising that they have a strong desire to end 350 years of Dutch oppression, and achieve full independence. Convinced that the Japanese occupation army would help them achieve their long-term dream, they co-operated. However, after two years of occupation, nothing changed."

— Yano Kenzo,

During his tenure as Governor of West Coast Sumatra, Yano established the Kerukunan Minangkabau (Gui Gan) as a consultation body between himself and Minangkabau leaders. The Kerukunan Minangkabau was established by Yano on 1 October 1942. Kerukunan Minangkabau met regularly at the governor's residence. Represented from each district, subdistrict, head of nagari, head of adat, scholars, youth, and the intelligentsia, its members consisted of 10 to 20 people. Its members were representatives of ulama, politicians, traditional leaders (including datuks), and academics who acted as an informal advisory board to the shūchōkan. Gusti Asnan referred to Kerukunan Minangkabau as the early House of Representatives (DPR). When the 25th Army Command issued an order for the establishment of a regional representative councils (Japanese: 州参議会, romanized: Shū Sangi-kai) in each shū on 8 November 1943 for the Central Advisory Council, the civilian government of West Sumatra continued the existing Kerukunan Minangkabau as a Shū Sangi-kai and Muhammad Sjafei was appointed chairman, supported by the 25th Army. Within the council, Yano Kenzo allowed criticism of the local Japanese government for insight in governance, unheard-of within occupied Asia.

The occupation government adopted a different attitude toward Islamic groups compared to its approach to nationalist movements. Islam, practiced by almost the entire population of West Sumatra, held significant influence over the society. Recognizing that much of the resistance against Dutch rule in West Sumatra had been led by these religious groups, such like during the Padri War, the Japanese saw Islam as a useful tool to embed their influence within the West Sumatran community. Due to this tolerance and in response to the transfer of power to the Japanese army, the Minangkabau ulama group initiated the establishment of the Minangkabau Higher Islamic Council (MIT). The MIT was established under the leadership of Syekh Jamil Jambek, with Haji Mansur Daut and Datuk Panglimo Kayo serving as secretaries. Japan's lenient attitude toward the faith, religious practices, and traditions of the West Sumatran people was driven by the hope that they could use these elements as tools to further their own agenda—specifically, the Japanization of West Sumatra through local beliefs and religion. Ahmad Husein noted that this assembly was established as a forum where the scholars deliberated on the politics of the Japanese government. Meanwhile, according to Datuk Palimo Kayo, the MIT was born thanks to the awareness of reformist ulama figures about how dangerous Japanese rule was. Established in 1942, the organisation elected Sulaiman Ar-Rasuli as chairman. With the aim of gathering all the forces of struggle of the Minangkabau Muslims, the MIT Minangkabau received the support of the entire Minangkabau people. Leaders of Islamic organisations at the time such as Perti and Muhammadiyah were united in resisting Japanese politics.

To gain acceptance from the people, the Japanese tried to approach the ulama group and give them a place in policy-making. The Japanese designed the formation of the Masyumi organisation at the centre. Religious Affairs Offices were established in each prefecture called Shu Muka. The clerics were given a special training programme called Kiyai Koshokai to prepare them to become Japanese propaganda tools. The "Principles Concerning Military Government in the Occupied Territories" (Senryochi Gunsei Jisshi Yoko) issued by the Japanese authorities on 14 March 1942 stated, "that religions should be respected as far as possible in order to keep the minds of the people stable... Muslims, should be given special attention in order to make use of them in order to grip the minds of the people". The occupation government adopted a tolerant stance toward Islamic organizations such as Muhammadiyah, Perti, and others. They sought cooperation from Islamic scholars (ulama), allowing them to continue their activities. Religious schools, including Muhammadiyah and Perti schools, were permitted to continue their educational efforts. The many madrasahs and suraus (Islamic study centers), which were dependent on their religious leaders for survival, were also allowed to carry on their educational and religious practices.

Minangkabau clerics took advantage of the offer of cooperation with Japan to gather the strength of the Minangkabau Muslim struggle against the colonisers. The Japanese gave the Minangkabau MIT a place in policy-making, including appointing Mahmud Yunus to represent the Minangkabau MIT as a resident advisor. In addition, several members of the assembly were invited to attend the Greater East Asia Islamic Congress in Singapore.

"...The Dutch do not allow us to be soldiers for them, but the Japanese do. Entering the Giyu Gun will be useful for us to fight them."

— Syekh Abbas Abdullah,

Despite encouraging the people to help the Japanese, the Minangkabau ulama at the same time fostered the growth of Indonesian nationalism. They encouraged young men to attend military training organised by the Japanese. Together with traditional leaders, they were involved in the recruitment process of prospective Giyūgun officers to minimise the influence of Japanese propaganda and replace it with the spirit of nationalism. Historian Gusti Asnan noted that their involvement in the selection of officers was to select candidates who were over 25 years old to 30 years old and insert the spirit of love for the country in the Giyūgun march. "They wanted the candidates to be mature enough to avoid the negative influence of the Japanese military upbringing." UIN Imam Bonjol academic, Irhash A. Shamad, stated that the pseudo-support given by Minangkabau scholars during Japanese rule had blinded the Japanese in seeing what was behind the support. Community leaders together endeavoured to achieve Indonesian independence. According to Irhash, fighting openly against the Japanese at that time was a wrong calculation, so the scholars motivated the people to fight quietly "while taking refuge behind the support for the Greater East Asia War echoed by Japan."

Within a year of the occupation, the Japanese shifted the focus of their policy from consolidating power and controlling the occupied areas in Southeast Asia to preparing to defend the region from Allied attack. Sumatra with its rich oil fields in Palembang and North Sumatra was particularly important in this regard. Strategically, Sumatra was also considered important due to its geographical position facing the Indian Ocean, especially the northern part of Sumatra's West Coast being the most vulnerable area from the two allied attacks of India and Ceylon. To implement these objectives, it was necessary to guarantee security and order from physical force, violence, and political conciliation. From mid-1943, the Japanese strategic plan anticipated an Allied counter-attack from Ceylon through the Andaman and Nicobar Islands. Consequently, the defense of Sumatra centered around the west coast, particularly the northwest coast, and on the islands of Nias and Sabang. The 4th Division was stationed in Padang to counter potential attacks from the west and to serve as a reserve force for northern Sumatra. Additionally, the 25th Brigade in Tapanuli stationed a third of its troops on Nias Island and deployed a sizeable force to the Mentawai Islands. Even so, the Japanese 25th Army had sought to mobilise the population's power for the Japanese cause.

In November 1943, the 25th Army Headquarters planned out on how the Voluntary Army of the Southern Area Land Army Command would work. The plan calls for the formation in four separate areas (later one more area was added), with each four Giyūguns formed independently under different leadership. This reflected the relatively high degree of regional autonomy that characterised the Japanese occupation of Sumatra. At first the 25th army tried to use the mercenary system to supplement its armed forces, however the system failed to bring results; with it failing to supplement the strength of the armed forces. Chatib Sulaiman then proposed to Yano Kenzo over the formation of a native army in West Sumatra instead as a way to supplement the strength of the Japanese army given the chance. This led governor Yano Kenzo to believe that it was the ideals of independence, not money, that drove the natives to fight and so suggested the idea to Tanabe. After the Army Command based in Saigon, Vietnam issued an order to form a Kyōdo Bōei Giyūgun on 8 September 1943, the 25th Army Commander, Tanabe, gave full authority to the Governor of West Sumatra to implement the formation of a native army. Given the opportunity, Yano Kenzo used this mass recruitment campaign to help and promote the propagation of the ideals of Indonesian independence in West Sulawesi. Thus the Giyūgun (Indonesian: Laskar Rakjat, Japanese: 義勇軍, lit. 'Volunteer Army') was established in Sumatra. Training included marching, Judo, Kendo, Japanese language, and Seishin lectures. According to Lebra, the propaganda emphasis was on fighting for one's country and co-operating with Japan in the Greater East Asian neighbourhood.

On 14 October 1943, Chatib Sulaiman led and pioneered the formation of a committee for the formation of the Giyūgun called Giyūgun Koenkai. To support this effort, Chatib Sulaiman traveled extensively around West Sumatra, recruiting prospective Giyūgun officers, and frequently shuttling between Padang and Bukittinggi. This committee under Japanese supervision screened prospective volunteer officers to be formed. In accordance with the structure of Tungku Tigo Sajarangan as a traditional Minangkabau leadership institution, the responsibility of recruiting prospective Giyūgun officers was handed over to three prominent leaders of West Sumatran society, namely Ahmad Datuk Simaradjo, from the ninik mamak element; Chatib Sulaiman, from the cerdik pandai element; and Hadji Mahmud Junus, from the alim ulama element. Together, they convinced the officers that the military training provided by the Japanese was aimed at achieving the ideals of Indonesian independence. Young men in Minangkabau were encouraged to become Giyūgun troops to receive military training from the Japanese. With the encouragement of traditional and religious leaders, many young men registered to become Giyūgun. Among those listed were Dahlan Djambek, Ismail Lengah, Syarif Usman, Dahlan Ibrahim, Syofyan Nur, Syofyan Ibrahim. A. Talib, Nurmatias, Sayuti Amin, Alwi St. Marajo, Syefei Ali, Mahyuddin Tonek, Burhanuddin, Munir Latief, and many others. From here there were around 20,000 who applied for the Giyūgun, but only 1,000 rations were available. Great encouragement for the development of the Giyūgun was given by Yano at a large meeting on 20 November 1943 in Bukittinggi. Finally he was able to influence the penghulu, who had been able to recruit at least another 20,000 soldiers from each member of his descendants. The call of the penghulu was well received by his people group.

The Giyūgun Koenkai became the only military force established by the Japanese in West Sumatra. The Giyūgun force was initially formed in Padang and the coastal areas, trained by the 37th Infantry Regiment of the 4th Osaka Division in 1943. The Giyūgun Section (Giyū-han) led by Major Akiyama was formed within the division staff office and there the basic outline was made. Later in January 1945 when the 4th Division was transferred to Thailand, the 25th Combined Brigade was transferred from Tapanuli and stationed in the Padang area. With this change, the Giyūgun was placed under the command of this newest Japanese garrison. Prior to the formation of the Giyūgun , a meeting was held between Yano Kenzo and local nationalist leaders, the Japanese announced the insistence on the formation of the Giyūgun. Soon after, an association called Giyūgun Kensetsu Honbu (Headquarters for the Establishment of the Giyūgun) was organised in Padang with Chatib Suleiman, a nationalist figure, as its chairman. The Giyūgun Kensetsu Honbu engaged in propaganda for the Giyūgun through newspapers, radio, films, and mass meetings. The association also assisted in the recruitment of cadres. Afterwards, the name of the organisation was changed to Giyūgun Koenkai (Giyūgun Support Association) and other nationalist figures such as Muhammad Sjafei and Suska also joined. With the help of this organisation, qualified young men were selected as potential cadres. Finally, training began in Padang in February 1944. The training of candidates began in two batches at Bukit Ambacang in Bukittinggi.

During Dutch rule, the Minangkabau people had very few skills and experience in the Royal Netherlands East Indies Army (KNIL). This was partly due to the Minangkabau culture of not having many military careers and also due to strong nationalistic sentiments against the Dutch. According to Audrev Kahin, only one of those recruited as Giyūgun cadres, Ismael Lengah, had received formal Dutch military training as a member of the Stadswacht, the city guard established in Padang in the last months of Dutch rule. Therefore, Giyūgun training provided an important missing element if any realistic opportunity for West Sumatrans to oppose a repeat of the strong Dutch takeover of their previous hold on the area. After three months of training, in May 1944, the cadres were sent to their place of appointment and began organising the company by recruiting local soldiers. At the time of the Japanese surrender, four infantry companies (in Talu, Pariaman, Painan, and Padang), a machine gun company (in Emmahaven), a mortar company (in Padang), and a howitzer platoon (in Lubuk Kilangan) were organised in the West Coast Residency under the auspices of the 4th Division. Since a company consisted of about 200-250 soldiers, the number of soldiers at the end of the war was estimated at 1,500‒2,000. Yano Kenzo wrote that the number of qualified applicants was very high, while the quota prepared by the army was only about a thousand. Each Company had several platoons and was stationed in different places, though the majority was stationed in Padang as the Japanese army initially prioritized coastal defense. Led under the 4th Division, its main base led by Captain Sasaki and later on by Major Akiyama.

As the war situation became increasingly unfavourable for Japan, it became necessary to strengthen defences around the 25th Army Headquarters by building fortifications in the mountainous interior. Thus another a separate Giyūgun group was organised in the Bukitinggi area. Under the direct supervision of the 25th Army Headquarters in October 1944, the Giyūgun's formation was about a year later than the other Sumatran Giyūguns. Cadre training began in October 1944 with 200-300 cadets at Bukit Ambacang, on the outskirts of Bukitinggi. After the training, 35 cadets were appointed as non-commissioned officers. All cadets were then divided and organised into 8 companies in the internal area of West Sumatra. The Bukittinggi Giyūgun troops were strategically stationed across several locations. Gulai Bancah, Baso, Padang Panjang, Koto Baru, and Batusangkar, with each site primarily hosting infantry corps. Baso also housed an engineering corps, while Padang Panjang served as the base for the communication corps. Additionally, there was also another artillery company and an engineering company. All companies were placed under command of the Bukittinggi Defence Garrison (Bukittinggi Bo'eitai) under the 25th Army with Colonel Harada as commander. The 35 non-commissioned officers were then recalled and received higher training. Eight were promoted to second lieutenant (shōi), three to high non-commissioned officer (Jun'i), and the rest to sergeant major (sōchō). By then, Japanese propaganda intensified in 1944. The various groups were united in the Hōkōkai, led by Muhammad Syafii and Khatib Sulaiman from the nationalist or educated movement; Datuk Parpatih Baringek and Datu Majo Uang from the tradition group; and Djamil Djambek and Sutan Mansur from the religious group. The Giyūgun Koenkai (later supported by the Giyūgun Koenbu), an association of Giyūgun supporters, was formed as a liaison between civilian and military leaders. The organisation has its headquarters in Jalan Belantung, Padang, and established branches in all districts, sub-districts and nagari. Haha No Kai, the women's wing of the Giyūgun led by Rasuna Said and Ratna Sari, was established to prepare supplies for fellow officers. The women's activities included collecting donations of rice from the community, from the savings of a handful of rice to be cooked each day.

By the time of the proclamation of independence, the Giyūgun had organised two drills for its officers. The first batch included Ismael Lengah, Dahlan Djambek, Sjarief Usman, Dahlan Ibrahim, A. Talib, Sjofjan Ibrahim, Munir Latif, Kasim Datuk Malilit Alam, Nurmatias, and Ahmad Hussein. The second batch included Kemal Mustafa, Sjoeib, and Zaidin Bakri. In 1945, 11 Giyūgun second lieutenants and three young lieutenants were appointed in Bukittinggi and four second lieutenants in Padangpanjang. At the same time, 20 officer candidates were appointed with the rank of sergeant-major (sōchō). These Giyūgun units were then organised into companies and allocated along the coast of West Sumatra, from Muko-Muko to Tiku. Apart from the Giyūgun officer education, the Japanese army in West Sumatra also educated 11 candidates from the Chūgakkō (lit. 'Middle school') in Padang. Among them were Hasnan Habib and Munafri Munaf. For village security guards, Bogodan, as well as assistance personnel for the police, Keibuho, were also trained. Taking account to auxiliaries and other formations, Brig. General Saafroedin Bahar estimates the total number approved for training was projected to be 5,000 people.

On 24 August 1944, Japanese planners did correctly assessed an Allied attack originating from Ceylon under the initiation of Operation Banquet. However, the attack took the form of minor bombing raids rather than an impending amphibious landing as Japanese planners expected. Commanded by Rear Admiral Clement Moody, the operation included bombing raids over Japanese positions in and around Padang, targeting the Padang airfield, the Indaroeng cement works, and the harbor facilities and shipping at Emmahaven. The second Allied attack on the Emmahaven took place in March 1945 at 06:30. This attack on Emmahaven lasted about 20 minutes, bombing and shelling ships that were docked and loading coal. As a result, three large and small ships were sunk and many “coolies” who were working to load coal became victims. On the Japanese side, several Kaigun (navy) men were killed. During the Allied attacks on Indarung, Tabing airfield and Emmahaven, Giyūgun units participated for the first time in these Allied attacks, without suffering any casualties. Air Bangis also experienced cannon fire from Allied warships, mostly aimed at the hills and the boats and sloops at anchor. These Allied gunfire did not meet with the slightest resistance on the part of the Japanese soldiers as they were mainly manning and preparing positions inland for a possible Allied landing, which did not happen. The Allied warships departed after sinking the boats, barriers, and lifeboats. In reality, the Allies had largely avoided the Dutch East Indies and opted to focus on the Central Pacific and the South-West Pacific, as previously agreed from the Casablanca Conference.

Another incident incident involved a company of Giyūgun soldiers stationed in Mukomuko, where Dahlan Ibrahim, a prominent independence figure, once served as the Vice Commander. Dahlan Ibrahim had been responsible for forming Giyūgun companies since his stationing in Painan, eventually being based in Mukomuko until the Japanese surrender. The Mukomuko Giyūgun Company received a report from the Seinendan, a pemuda paramilitary organization, about a suspicious light seen at sea. Upon investigation, it was discovered that an Allied submarine had dropped off some men in a carriage boat. The Giyūgun soldiers immediately fired upon the boat. After the submarine disappeared, the body of an Australian soldier who had apparently been dropped off as a spy in Mukomuko was found.

As tensions in the Pacific War escalated, Japan increased its control over the population. Japan's initial ‘friendliness’ towards the local people began to reverse. Moreover, the financial needs for the war against the Allies increased, while the source of income did not increase. Therefore, the policy of exploiting people's labour for the benefit of Japan began to appear. People were forced to work in factories. Cruel tortures against dissenters by the Kempetai were seen everywhere. The freedom of the people's leaders was restricted, and organisations and associations were only allowed to carry out service-oriented activities for the benefit of Japan. It is through these harsh acts done by the Japanese occupation government led to tensions between the Japanese military authorities based in Bukittinggi and Governor Yano Kenzo who headed the West Coast Sumatra provincial civilian government in Padang

In Bukittinggi, the Japanese constructed the largest radio transmitter on the island of Sumatra, intending to use it as a way to serve as a propaganda tool to raise the spirits of the people and garner support for the Japanese war effort. In an effort to meet the need for labour, the Japanese authorities imposed compulsory rōmusha labour on the population for various Japanese purposes, such as building roads, railways, bridges, fortifications, and protection tunnels. In addition, civil servants, merchants, school children, and residents who did not participate in forced labour were subjected to Kinrohoshi, voluntary work to collect river stones, sand, and gravel and transport them to the necessary places. Japanese bunkers and protection tunnels were found in Padang and Bukittinggi. The Muaro-Pekanbaru railway line was the result of forced labour involving approximately 6,600 prisoners of war and 30,000 rōmusha workers. Through education, the Japanese made fundamental changes in West Sumatra. Schools were mobilised for Japanese interests and Japanization policies were implemented. Indonesian was made the language of instruction in schools to introduce Japanese culture and at the same time, students at various levels were taught Japanese. Students were also trained in Taisō (a type of Japanese morning exercise), Japanese-style mutual aid, and even military training. These activities were actually carried out more than studying. The youth were trained militarily for the Keibōdan (police auxiliaries), Seinendan (village security guards), Heihō (Greater East Asia soldiers), Rōmusha (Greater East Asia builder soldiers), and the Giyūgun. Meanwhile, the educated classes, especially teachers, civil servants, and students were made into "new Japanese." Seikeirei (bowing to the emperor's palace in Tokyo) and Mukto (commemorating the spirits of Japanese heroes) are performed at certain times. These activities are usually done after hearing the speeches of the shūchōkan or Japanese officials. Keirei (standing salute) is mandatory whenever passing Japanese dignitaries, even in cars. The Gregorian calendar is replaced by the Japanese imperial year, which is 660 years apart, while the time signature is adjusted to Japanese standard time, which is about 2.5 hours apart from Tokyo time.

As Japan's military power began to decline sharply from the first half of 1944, the impact on the local population in occupied territories in Sumatra became increasingly severe. One of the most significant factors exacerbating the situation was the Japanese military authorities' decision to increase the money supply without any backing by real assets. This policy led to severe inflation, drastically reducing the purchasing power of the local population. Tanabe, a military man, often sought Yano Kenzo's opinion because he himself was “dissatisfied with the military reports and policies issued by the Military Government Headquarters." In addition to "being very interested in policies concerning the indigenous people.” The potential devastation wrought by this monetary policy struck Governor Yano who strongly protested against its impact on the local people, arguing:

"Anyone can find on the first page of the country's financial books that the prices of goods will rise in line with the increased supply of war currency. A doubling of the amount of money has caused the price of goods to triple."

— Yano Kenzo,

Mounting economic pressure erratically made by the Japanese military led to Yano Kenzo, reign in protest. Despite Yano's protests, economic pressures continued to mount as Japan's military setbacks worsened in the following months. The Japanese military government intensified its demands on the Sumatran people, requiring local officials to supply foodstuffs and other materials at increasingly higher fixed rations. Additionally, they were tasked with finding men to work as "coolies" on Japanese defense construction projects. Obtaining household necessities became harder due to the war effort's demands. All staple foods were prioritized for the Japanese forces engaged in the Pacific war, forcing most of the people's agricultural products to be surrendered for war purposes. Granulated sugar became a rare commodity as it had to be imported from Java, and the locals had to resort to using 'Lawang' sugar, a type of local red sugar cane that had been ground into a powder. Salt was also scarce, with the briquetted salt made in Madura becoming hard to find, leading people to make their own salt. Basic hygiene products were difficult to obtain, and many people had to use substitutes like rice straw ash or kenikir fruit for soap. Kerosene, essential for lighting, was in very short supply, prompting the widespread use of coconut oil lamps or burning rubber as an alternative. Matches were also hard to come by, so people resorted to using fire hatches, striking a hard stone with iron to create sparks and light fires.

Transportation was another significant issue. Bicycles were often used with dead tires, and cars or buses no longer used petrol but instead relied on oil made from rubber, which emitted a foul smell. The shortage of clothing was particularly acute, especially in the later years of the war. Urban dwellers, who typically had more old clothes, could somewhat cope, but villagers, especially farmers who could only afford to make or buy new clothes once a year, suffered greatly. Many villagers were too ashamed to go out, and if they had to, they wore makeshift body coverings made of tarok bark or burlap. The price of cloth skyrocketed, with just a few pieces of batik cloth being valuable enough to exchange for a paddy field. Although there was some cloth, much of it was stored in Japanese warehouses in preparation for the war, exacerbating the shortages. The difficulties in transportation also affected trade between regions. Moving goods was challenging due to the lack of transport equipment and the damaged infrastructure, including railways. Trade required special licenses, particularly for goods transported to Java. The condition of the railway tracks was so poor that it led to two significant accidents in West Sumatra during the war: one at Pakan Raba'a near Padang Panjang in 1944 and another in Lembah Anai.

By the closing stages of World War II, economic hardship imposed by the 25th Army and widespread pressure felt by the people of Sumatra led to growing disillusionment and discontent toward the Japanese occupying forces. This unrest prompted some to take up arms against the occupying forces. In South Sumatra, Giyūgun officers held secret meetings in Lahat in December 1944 and January 1945, planning to launch an armed rebellion at an opportune moment across the province, and later spreading. However, the plan was thwarted when the Japanese army discovered the plot. In July 1945, Giyūgun members in Pematang Siantar, led by 1st Lieutenant Hopman Sitompul Siantar, openly defied orders from Japanese officers and trainers, intending to continue and escalate the resistance into an armed rebellion. This effort, however, was swiftly suppressed when Sitompul was arrested by the Kempetai and detained in Bukittinggi. Meanwhile, in Bukittinggi itself, various youth groups and nationalist factions began rallying to form an anti-Japanese resistance movement. Seeking independence, these groups operated both covertly and openly, as public sentiment turned increasingly against the Japanese, particularly with the realization that the Allies were gaining the upper hand in the war and dissatisfaction with the direct rule of the 25th Army over the region.

During the Japanese occupation, many West Sumatran women were victims of Japanese army violence, especially sexual exploitation. Acts of violence against women have occurred since the first days of the Japanese army's arrival. The rules of values that respect women were violated by acts such as coercion, kidnapping, and rape, to forcibly making comfort women or Jugun ianfu. Japan could no longer bring in comfort women from their own country so instead, Japan made a policy to force women to serve as comforters for the needs of its soldiers in the brothels they set up. A government policy issued in 1938 said that every battalion needed to have a brothel, so that Japanese soldiers could concentrate on the war.

Overcoming this form of coercion was attempted by local leaders. In 1942, while in Padang, Sukarno discussed with several ulama and gave permission to practice prostitution for Japanese soldiers. "Solely as an emergency measure, in order to protect our girls, I intend to make use of the prostitutes in this area. In this way, foreigners can satisfy their desires and the girls should not be disturbed, "explained Sukarno. The granting of this permit is marked by the existence of brothels in several places in West Sumatra such as Padang, Bukittinggi, and Payakumbuh. Generally, sex workers come from non-West Sumatran women, most of them come from women who were brought by the Dutch to work and their lives were neglected. Sukarno acknowledged that it was his administrative act as the de-jure leader of the Indonesian people. He congratulated himself on "simultaneously enhancing the women's income, sating the lust of the invaders, and thereby protecting virtuous Minangkabau maidens."

Sukarno's granting of licenses to brothels was originally intended to stop the Japanese army from harassing West Sumatran women. The beginning of this program was to gather 120 prostitutes as "volunteers" to be penned in a special camp for service to Japanese soldiers. However, the number of women permitted to operate in Japanese camps was insufficient to serve the thousands of soldiers. "To get the comfort women provided, Japanese soldiers had to buy queue tickets. Even for one woman, there were up to four or six people queuing in one night," testified one Kaigun Heiho with the rank of corporal. With these tickets, Japanese soldiers were organized while waiting their turn to be with the women they desired. The stark inequality in the number of women available caused dissatisfaction among many Japanese soldiers, prompting them to coerce many West Sumatran women. To obtain women, the Japanese resorted to coercion, abduction, rape, and persuasion. They did not hesitate to take women even if they were married, regardless of whether they were sitting with their husbands at the time.

On August 15, 1945, many people in West Sumatra were unaware of Japan's surrender. However, those who were observant noticed a change in the demeanor and behavior of the Japanese. The typically rigid and determined Japanese soldiers appeared melancholic and withdrawn. In the Giyūgun units, the atmosphere had also changed; Weapons had been collected on August 10 in Padang, under the pretext of exchanging them for new ones, coinciding with a break in training due to fasting, were never retrieved back. They were later disbanded irregularly on August 16, 1945, and in some units even later, without any formal ceremony or explanation. Members of the Giyūgun were simply told that the war was over, but there was no declaration of defeat or surrender, leaving many confused and uncertain about the situation. The Giyūgun members were then sent back to their villages, traveling on foot or by carriage, with the Giyūgun members in worn-out and tattered clothing. An account by Abdul Halim (Aleng), a 2nd Lieutenant of the Bukittinggi Giyūgun and former teacher of the HIS Muhammadiyah, was once summoned to the company office in Bukittinggi on August 15. Upon requesting permission to return to his village to see his seriously ill grandmother in Matur, his company commander, 1st Lieutenant Okura, surprisingly granted him leave and even allowed him to rest in the village for an extended period. He then shared this unexpected gesture with his colleagues in Bukittinggi, to which puzzled many Giyūgun members who had not yet grasped the reason behind the sudden change in their commanders' attitudes. One of the first Indonesians who have heard of the surrender was Jahja Djalil, aprominent activist, courier, and reporter in the region. He was informed by Kurihara, a Japanese journalist working for Kita Sumatora Shinbun in Padang, that the war had ended.

By mid-August, the attitude of the Japanese in the region had shifted noticeably. They began to approach Indonesians more amiably, but this change was met with skepticism due to the previous harshness and brutality of the Japanese. During a regular meeting at the Japanese Governor's home, Sutan Mohammad Rasjid and other officials from the High Prosecutor's Office, including Dr Liem Gim Tjiang, Idroes, and Ismail Karim, were informed by the Governor, Hattori Naoaki, that Japan had laid down its arms and was seeking peace. In Muko-Muko, Northern Bengkulu, Dahlan Ibrahim, the Deputy Commander of the local Giyūgun Company, received news of the war's end on 20 August 1945. On 22 August 1945, at 10:00 AM, all Giyūgun troops and companies in Bukittinggi and the surrounding areas were officially disbanded. The Giyūgun Koenbu was also disbanded after members notice its operations was without any signs of Japanese supervision or oversight.

The first news about the Indonesian proclamation of independence came from Indonesian employees working at the Post, Telegraaf, en Telefoondienst (PTT) offices in Padang and Bukittinggi. As soon as the traders and educated classes of West Sumatra received news from Aladin, an employee of PTT Padang, that Sukarno and Hatta had proclaimed Indonesia's independence on 17 August 1945 in Jakarta, word began to spread rapidly by word of mouth. Although at that time there was no direct contact with the leaders in Jakarta to clarify, the Indonesian youths (Pemuda) felt responsible for spreading the supposed news of the Proclamation of Indonesian Independence. Indonesian youths began printing pamphlets in secrecy and began to widely distribute it in Padang and several other cities in West Sumatra, and thus the Proclamation of Indonesian Independence became widely known to the public in a relatively short time. Immediately, Jahja Djalil and his colleagues went to see Abdullah Halim. Abdullah was of the opinion that the news of the proclamation should be disseminated immediately and that the views of some of the scholars in Padang should be examined. Many of those contacted were cautious of it being possibly false information, but Sutan Mohammad Rasjid and Dr Athos Ausri gave strong encouragement.

With regard to the Proclamation of Independence, Jahja Djalil asked Yano Kenzo. The former Japanese governor resting in Padang confirmed the existence of the Proclamation of Independence but emphasized that it was now a matter for the Indonesian people, not Japan. When asked for his opinion on leadership in the newly independent West Sumatra, Yano recommended Mohammad Sjafei for the position of Resident, citing Sjafei's roles as Chairman of the Chūō Sangiin of Sumatra and Chairman of the Shū Sangi-kai of West Sumatra. Yano expressed that he did not see anyone else more suitable for the role and stated that he would not be returning to office. He ordered that his opinion be conveyed to Moehammad Sjafei himself.

British troops landed in Padang on 10 October 1945, led by Major General Henry M. Chambers of the 26th Indian Infantry Division and accompanied by none other than Major General Adriaan Isaac Spits, as the Dutch representative. On 21 October, these Allied officers accepted the surrender of all Japanese military forces in Sumatra, signed by Lieutenant General Moritake Tanabe, commander of the 25th Army, and Vice Admiral Sueto Hirose, who orchestrated the Japanese invasion of Batan Island in the Philippines and stayed in West Sumatra.

Before Japanese troops, who had been disarmed by the Allies in West Sumatra, were dispatched to Pekanbaru for their eventual return to Japan, they were initially gathered in Baso and Cubadak near Payakumbuh. Many of these soldiers seemed hesitant to return home, preferring to assess the situation before making a decision. Their reluctance to leave stemmed from various personal reasons, and some even expressed a desire to settle down in Indonesia. As the situation unfolded, a number of Japanese soldiers approached members of the People's Security Army (Tentara Keamanan Rakyat or TKR) and sought to integrate into local life. Some found employment in workshops, while others became advisors at training grounds. There were also reports of officers committing suicide (Harakiri) due to the shame of their defeat. A subset of these Japanese soldiers decided not to return to Japan and were willing to assist in Indonesia's struggle for independence. They were distributed among various agencies in need, including large workshops focused on repairing weapons. Workers from Sawahlunto also participated in these efforts, repairing and manufacturing equipment under the guidance of the Japanese who had chosen to stay.

However, not all Japanese soldiers who remained were sincere in their intentions. Some were involved in sabotage or acts of treason. Some even refused to surrender. As suspicions grew, the Commander of Division IX, Colonel Ismael Lengah, ordered the arrest of approximately 127 Japanese soldiers. The operation was carried out by the Commander of the Army Police (PT) Division, Major Syafe'i, who gathered the suspects for examination in the Payakumbuh area.

According to Akira Oki, the legalisation of Indonesian as the language of instruction in schools affected the development of the Indonesian language and led to a sense of unity among the people. The education provided by the Japanese accelerated the maturation of Indonesia's independence efforts, something that the Japanese authorities in West Sumatra did not realise. In the political field, the Japanese had bequeathed the form of the representative institution Kerukunan Minangkabau, which brought together traditional and religious leaders as advisors to the resident. Although they had no official authority in the government, they could colour the policies of the Japanese rulers in West Sumatra, and secretly instil national ideals in the people. In the military field, the Japanese provided military training through the Giyūgun volunteer army. The first batch of Giyūgun officers would later play a role in the establishment of the Indonesian armed forces after independence and most of them gained strategic places in the military hierarchy during the revolutionary period.

Audrey Kahin notes that co-operation between adat and religious leaders during the Japanese occupation of West Sumatra formed a link in the chain of territorial relations and a foundation for mutual understanding, something that was particularly valuable in the years after independence.

• Invasion of Sumatra
• Muarakalaban–Muaro–Pekanbaru railway
• Japanese colonial empire
• Japanese occupation of the Dutch East Indies

• Media related to Japanese occupation of West Sumatra at Wikimedia Commons