The strongest delinquent who picks up the baby floating down the river, and is chosen to be the boy's earthly "Father". He is known for being "Kata-Middle School's violent ogre." He was picked to become Beelzebub's father because he possessed the qualities of the ideal parent for the future Devil King: strong, arrogant, and thinks-nothing-of-fellow-man. He seems to have a lot of enemies and no friends, except for his classmate Furuichi. He is currently a first year at Ishiyama High.
Oga is easily aggitated and is always willing to fight, unless it will bring out the Zebub spell. He appears to have his own skewed idea of what a 'man' should be like, and attempts to pass on these ideals to Be'el. Despite being called evil by almost every character of the series, he has shown to have a calmer and, if only slighlty, warmer side to him, shown when he speaks with Hilda about his position as Be'el parent and assuring Lamia that if Be'el ever got sick again he would call her immediately. He also seems to care, at least to some degree, about his classmates, as he quickly stopped Nene when she was about to fight Mikki, telling her she would lose if she did. He and Mikki seem to have some type of history together, yet Oga claims not to remember his old classmate. It is unknown if this is the truth as Mikki does not act suprised at Oga's statement. Oga, along with Furuichi, is an avid fan of the video game series "Dragon Quest" regularly making references to the series in the manga.