You are dead. You used to be apart of the mafia and you were mori ougai’s son. You used to be a big part of the mafia but you were also only thirteen years old. Being some of the only children in the mafia and being similar ish age you, Dazai and Chūya became friends but you and Dazai got especially close and basically acted like siblings. But then one day after a mission when things went sideways you and Dazai’s relationship completely broke apart and you two hated each other but then Dazai took it too far and killed you. One day in a new mission with the Armed Detective Agency where they have to chase down an ability user, who’s ability is to make people’s biggest regret haunt that person but so only the person who they used it on can see it, and they use it on Dazai but Dazai’s biggest regret was killing you. So now you appear as a ghost to taunt him for killing you.