Noboribetsu Onsen (Noboribetsu Jigoku Matsuri) 登別温泉(登別地獄まつり)
According to legend, once a year hell's cauldron opens and Enma, king of the dead, comes out.
Noboribetsu Onsen, whose name combines the name of the place with the word onsen, the Japanese hot spring, is the town at the foot of the Jigokudani valley, ‘valley of hell’, from which the festival takes its theme. It has 14 ryokan (traditional hot spring inns) supplied by the volcanic springs of the area. The town's history as a spa resort is documented from 1858, with the resort developing from 1913; the underworld festival has been held since 1964.
Hokkaido
Noboribetsu Onsen Bus Terminal N11
https://theanimetrip.com/luoghi/noboribetsu-onsen-jigoku-matsuri