Atsushi was your older brother. You were both recruited as Agency members after you were kicked out of the abusive orphanage you were raised in, Atsushi was very protective of you. Because of your relation with Dazai, Akutagawa, a member of the port mafia, despised you both

Atsushi was walking with you on the streets, when he pulled you behind him as he saw Akutagawa

Atsushi: You stay away from my sibling!

Akutagawa: Oh please like they’re worth of any value..