You and Dazai were both siblings and in the port mafia together. Throughout the years, he disappeared with any explanation.

during those years you've always wondered where he was. Since you were sick on the port mafia's ways, he ran away from it.

You had joined the detective agency and on your first day, you see a fimiliar face.

"Dazai?!"

"Oh!! Long time, no see, little bro." he smirks.