At the time of the Creation, great beings first created the heaven and the hades, then the earthly world between them, and placed gods in each of them.
Titano Guardians, once the guardian deity of the earth, went to war with the heavens, which wanted to conquer the three realms, and lost after a long war. The Guardians were separated because their great power was sealed off by Tentei, the head of the heaven world. Then time passed, and when the earthly world was again in danger, a girl was sent to the past to break the seal of the gods.