Minamiaso (南阿蘇村, Minamiaso-mura, literally "South Aso") is a village in Aso District, Kumamoto Prefecture, Japan. As of 31 July 2024, the village had an estimated population of 10,071 in 4821 households, and a population density of 73 persons per km. The total area of the village is 137.32 km (53.02 sq mi).

Minamiaso Village is located in the southern part of the Aso Caldera, in the Nango Valley between the Five Peaks of Aso and the outer rim of the volcano. On both sides of the Shirakawa River, which runs from east to west through the urban center, are residential and commercial areas, and cultivated land. Most of the area above 600 meters in elevation is covered by forests.

Kumamoto Prefecture

• Aso
• Nishihara
• Ōzu
• Takamori
• Yamato

Minamiaso has a humid subtropical climate (Köppen climate classification Cfa) with hot summers and cool winters. Precipitation is high, but there is a pronounced difference between the wetter summers and drier winters. The average annual temperature in Minamiaso is 14.4 °C (57.9 °F). The average annual rainfall is 2,922.8 mm (115.07 in) with July as the wettest month. The temperatures are highest on average in August, at around 25.5 °C (77.9 °F), and lowest in January, at around 3.7 °C (38.7 °F). The highest temperature ever recorded in Minamiaso was 36.2 °C (97.2 °F) on 8 August 2015; the coldest temperature ever recorded was −10.0 °C (14.0 °F) on 24 January 2016 and 8 January 2021.

Per Japanese census data, the population of Minamiaso in 2020 is 9,836 people. Minamiaso has been conducting censuses since 1960.

Historical population

Year Pop. ±% 1960 16,485 —     1965 14,636 −11.2% 1970 13,087 −10.6% 1975 12,797 −2.2% 1980 13,010 +1.7% 1985 13,285 +2.1% 1990 12,643 −4.8%	Year Pop. ±% 1995 12,864 +1.7% 2000 12,436 −3.3% 2005 12,254 −1.5% 2010 11,978 −2.3% 2015 11,503 −4.0% 2020 9,836 −14.5%
Minamiaso population statistics

The area of Minamiaso was part of ancient Higo Province. In the Edo Period, it was part of the holdings of Kumamoto Domain. Following the Meiji restoration, the villages of Chōyō, Hakusui, and Kugino were established on April 1, 1889 with the creation of the modern municipalities system. Due to declining birth rate, aging population and the opportunity to share administrative resources, discussions between the three villages (Chōyō, Hakusui and Kugino) began on April 1, 2003. The merger was complete on February 13, 2005, forming the village of Minamiaso.

Minamiaso has a mayor-council form of government with a directly elected mayor and a unicameral village council of 14 members. Minamiaso, collectively with the other municipalities of Aso District, contributes one member to the Kumamoto Prefectural Assembly. In terms of national politics, the village is part of the Kumamoto 3rd district of the lower house of the Diet of Japan.

The economy of Minamiaso is largely agricultural, with some tourism to its several hot spring resorts.

Minamiaso has three public elementary schools and one public junior high school operated by the village government. The village does not have a public high school, but there is one private high school.

JR Kyushu - Hōhi Main Line

• Tateno

Minamiaso Railway Company - Takamori Line

• Tateno - Choyo - Kase - Aso-Shimodajyō - Minamiaso Mizu-no-Umareru-Sato Hakusui-Kōgen - Nakamatsu - Aso-Shirakawa - Minamiaso-Shirakawasuigen - Miharashidai

• National Route 57
• National Route 325

• Official website (in Japanese)
• AsoFan.net
• Mt Torokko (Minamiaso Railway) (in Japanese)
• Minamiaso-mura Association of Tourism