Yomi is a spirit world adjacent to Hell and resides as the home of the Yōkai as well as the world containing the location of Maou's former prison, to those viewing it from the outside it appears to be a black hole-like sun that is absorbing all the light and colour in the Universe, Yomi is in a constant state of self destruction - destroying and repairing itself - but only stops when its opposite (the Human world and Spirit world) are in conflict and chaos.