Six-Faced World

The Six-Faced World (Roku-men Sekai, literally "Hexahedral World") is the world in which Mushoku Tensei takes place. It is shaped like a die: each of its six faces is a separate world ruled by its own God, and a seventh world of nothingness lies inside the structure. It was made by the dying God of Creation, whose attempts to build a single stable world kept producing distorted ones, until he had made six - the Dragon World, the Demon World, the Beast World, the Ocean World, the Sky World and the Human World - and stuck them together so that each world held the others in balance, with the Void World at the center.

He then divided his body into six alter egos who descended onto the six worlds and came to be revered as their Gods. After the war of the Gods only the Human World and the Void World remained, and the survivors of the other worlds fled to the Human World, which is why it is now home to many races.