The story follows Tatsumi Oga. He is a first year student at a school for juvenile delinquents called Ishiyama High. The story starts with Oga telling his best friend, Takayuki Furuichi, the strange story of how he found a baby. One day while doing 'laundry' by the river, he saw a man floating downstream. Oga pulled him to shore but the man split in half, revealing a baby boy inside. This baby turned out to be the son of the great demon king, and Oga has been chosen as the one to raise him, along with the baby's maid, Hilda. The drama follows Oga's life as he tries to raise the child while enrolled at Ishiyama High.
