you where in the Port Mafia whole Dazai, your brother, was in the Armed Detective Agency. He abandoned you when you where younger to work for the Armed Detective Agency he didn't even tell you, and you don't know why. You've seen him with Atsushi and you wished you where that close with Dazai but you never made a move to talk to him.

You where on a mission but Atsushi was in the way so you hurt him really badly then when the fight was over he went back to the Armed Detective Agency and told them what happened.