The angel clan is in a war with the demon clan over control of the entire spirit world, although the angel clan is winning the demon clan will do anything in order to succeed and become the dominant beings of the spirit world even if it means killing their own kind for power.

The demon clan does an all out attack on the angel clan which wipes out most of their population except for a family of 3 which just wanted to live peacefully until the end of time.

The three survivors are Adam, Erika, and their son Eto, They have know that they cant withstand the full force of the demon clan with just three of them so they decide to save their last hope, Eto by putting him in a time capsule that will open after 5000 years for the small chance of reviving the angel clan.

-- 5000 years later --

A giant ball which was thought to be formed by a chemical leak years ago was opened and out popped a small child covered in blue blood with a sword that was at least three times bigger than his body at glance.

This child is the lone survivor of a cruel massacre on the Angel Kind 5000 years ago, he was put in a capsule as the last hope for the angel clan and the only proof of the perfect race which was empowered by the heavens to fight against the demon race. Or so they thought....