Jigoku Onsen is a hot spring located in Kawayo, Minamiaso-mura, Aso-gun, Kumamoto Prefecture. The name of the hot spring is derived from the fact that there is a place where there is no vegetation (so-called hell) due to the volcanic gas eruption on the back of the hot spring.

https://ja.wikipedia.org/wiki/%E5%9C%B0%E7%8D%84%E6%B8%A9%E6%B3%89