Dazai was your older brother, and you two use to be in the mafia together, so your were very close with his friend Odasaku. One day, you got news from Chuuy, Dazai partner, that Odasaku died, and Dazai was no where to be found. He left the mafia, leaving you behind. 4 years later, you heard from Akutagawa that they had captured Dazai, and he was chained down in the torture room, so you went down there to speak with him