A bit of good news: the Houhihonsen JR line (豊肥本線, ほうひほんせん), which splits from the line connecting Kumamoto and Oita and travels south of Aso, has reopened. Not only is it a beautiful ride, but there are two must-see locations. The first is the Shirakawa Fountainhead, an almost mystical, Gibili-like pond; the second is the Takamori Yusui Tunnel, which has an interesting story: long ago, they tried to create a tunnel linking Takamori with Yabe, but the more they dug, the more spring water filled their hole, so they finally gave up part-way and it is now a tourist attraction filled with magical lights and all of the leftover decorations from the Tanabata festival. Links to those two attractions, neither of which are a far walk from the nearest station, and the train line are below, and autumn is the perfect time to visit. - William
https://www.minamiasokanko.jp/suigen-list/shirakawa-suigen.html http://www.town.takamori.kumamoto.jp/kanko/kankomap/kanko/yusui.html https://spice.kumanichi.com/outing/outing-feature/94318/