The story takes place in a microscopic world called "Floating World". This world is actually the remains of a gigantic god that fell in an ancient divine war. The mountains and rivers are the bones of the gods, the rivers are the receding blood, and the forests and tundra are the fungi and vegetation derived from the gods' bodies. The living beings "dust spirits" living here are tiny in size. They regard this divine corpse as the entire universe. They call the slow decay of the divine corpse the "Great Nirvana".
