I'm His Parent
After Oga came back from his training he introduce his new technique called the "Zebul Emblem" and "Super Milk Time" (He learn it while he was training with Saotome and Black Baby Beel and Baby Beel is fighting over the milk and Oga Decide to drink it himself so Black Baby-Beel And Baby-Beel doesn't have anything to fight on) to remove the divider between Oga and Baby-Beel. Oga suddenly became powerful after drinking the milk and the demon power from Baby-Beel increase and Oga defeat the two Pillar heads and after that he became unconscious and the Pillar Head Naga also fight Oga and Oga drink more of the milk then He and Baby-Beel merge and they became more powerful Oga Grew a wing and Scattered the Zebul Emblem to surround the Pillar Heads and at last he defeated the three Pillar Heads and the top of Himekawa's hotel was destroyed due to the explosion.
Aired 25/12/2011EP 48 - I'm His Parent

Beelzebub
Oga Tatsumi is a first year student in Ishiyama High, a notorious school for delinquents. One day he sees a man floating by, and the man suddenly splits in half to reveal a baby boy inside!
(Source: Crunchyroll)