The is a Japanese railway line in Kumamoto Prefecture, connecting Tateno Station in Minamiaso and Takamori Station in Takamori. It is the only railway line operated by third-sector railway company . The line traverses the southern part of Mount Aso caldera.
All stations are within Kumamoto Prefecture.
â The station name of Aso-Shimodajà  has changed three times:
With 22 kana, Minamiaso Mizu-no-Umareru-Sato Hakusui-Kà Âgen Station (Ã¥ÂÂé¿èÂÂæ°´ã®çÂÂã¾ãÂÂãÂÂéÂÂç½水é«ÂÃ¥ÂÂ駠|Ã¥ÂÂé¿èÂÂæ°´ã®çÂÂã¾ãÂÂãÂÂéÂÂç½水é«ÂÃ¥ÂÂ]) was tied with Chà Âjagahamashiosaihamanasukà Âenmae Station in Ibaraki Prefecture as the longest station name in Japan; however, since 2020, the record is held by Tà Âjiin Ritsumeikan University Station in Kyoto, with 26 kana.
The entire Takamori Line was closed following significant damage to track and infrastructure following the Kumamoto earthquakes in April 2016. A section of the line between Nakamatsu and Takamori resumed service in July of the same year.
However, the section between Tateno and Nakamatsu could not be reopened because of extensive earthquake damage to the track. The Ministry of Land, Infrastructure, Transport and Tourism estimated that a complete restoration would cost between 6.5 and 7 billion yen. After work was completed to restore the railway, the full line re-opened on 15 July 2023. Major work to reopen the line included the complete rebuilding of the badly damaged No. 1 Shirakawa arch bridge.
The single-track line was opened by the Japanese Government Railways in 1928. The only passing loop is at . Freight services ceased in 1984. Minamiaso Railway took over the line from Japanese National Railways (JNR) on April 1, 1986. It uses a simplified automatic railway signalling system. The line is not electrified.
The MLIT tested a DMV railbus on the line in November, 2007.
After the Takachiho line opened in 1972, construction of the section to Takamori continued until 1975 when flooding in the Takamori tunnel ( north of Takamori) resulted in work being suspended. Construction was formally abandoned in 1980.