Demon World

A world that has nine areas run by demons and a castle the King demon lives in.Each area has a sibling running it. The central area is a shopping district where humans can get items that can only be found here. There are gates to each area that are always locked to prevent humans from entering areas that would be dangerous to them. Each areas leader has the key to their gate, but not of the other brothers key. Yorou is the only sibling to have a key that opens all gates,even the gate to the human world.