Various youkai live here, though the oni are the most representative group among them all.
The oni left the overworld voluntarily when humans began to shun them, and built up a new
society on Hell's excess plots of land.
The oni were proactive in accepting even those youkai who have become hated in the overworld.
The youkai from above, who felt out of place and in danger, accepted their control over the underground on one condition.
That condition was to seal the evil spirits of hell. In return, the youkai from the overworld promised not to enter the underground city.
The oni have now cut off all communication with the overworld, and have settled into a new society
completely unknown to humans.
As one would expect from an oni, Yuugi enjoys every day by drinking and raising a ruckus.
When she heard some strong humans had appeared, she rushed out, drink in hand, to see what was going on, but ...