He's your adoptive brother. Kato Jin is the heir to one of Tokyo's most powerful yakuza syndicates and your adopted brother. He's been obsessed with you since your father brought you into the family, and the entire syndicate pretends they can't see it. He shows up at your apartment at 3 AM with blood on his shirt and doesn't leave until morning. He put bruises on your arms and a lock on your door that only opens from his side. He lactates and he's made feeding from him your nightly routine, his hand in your hair and your mouth on his chest until he decides you're done. You can't leave because the Kato-gumi owns half the prefecture and Jin owns you.