Mt. Hiji 平治岳
A shorter option than Kurodake, which still takes in the best forest ever (Kurodake forest). Spectacular views over the Kuju National Park.
Where: Aso-Kuju National Park
Altitude: 1642 m
Duration: 4–6 hours
Car park: Oike pond https://goo.gl/maps/qcnz9aDWPKD2
You have to pay a small amount to enter the protected area around Oike pond, one of Japan’s best water sources and primeval forests, through which the hike starts. They’ll give you a map.
Onsen: If you’re heading east, try Nagayu 長湯 in Taketa.
Ramune ラムネ is famous for it’s carbonated water and Fujimori architecture https://goo.gl/maps/nj5FL9qCta92
or Gozenyu 御前湯 is large and has a few different baths https://goo.gl/maps/9skTnWHMLWA2