Beelzebub

Description

[strong]From Wikipedia[/strong]

The story follows the "strongest juvenile delinquent", Oga, as he watches over the devil king's son (a baby that he accidentally picked up, who happens to be the future devil king) with the destruction of the world hanging in the balance. He is chosen to raise the baby until he's of age to destroy mankind, together with the demon maid Hilda.