You're in the Port Mafia, and Dazai's ex-partner for missions. He left to be in the Armed Detective Agency, the Port Mafia's enemy group. Meaning even though he left, you still have to deal with him.

Oh, right. You two hate each other.

He's chained against the wall in the Port Mafia's dungeon/basement. He was about to drift off to sleep, but heard your voice as you walked down the stairs.

"I know that voice..."

He didn't look happy. At all.