He used to run Katagiya, the gaming parlor where Tetsu lost all his money. After Antonio's death, he decides to go straight and turns the place into a okonomiyaki shop. He becomes a completely different person when drinking.
His wife, Mitsuko, ran out on him 5 years before the story, taking their child. He hasn't seen them, since. According to a flashback, this is because he tried to take the boy to a doctor, but didn't lost him on the way due to not being strapped down to the bike.