It happened. He got chosen. He agreed. He didn't want to cause any troubles for Agency.

Dazai and Chuuya got back to Yokohama after Mersualt, Dazai didn't even go to Agency to greet them or something. He just went with Chuuya to port mafia. Dazai knew it was him. He would volonteer anyways if it wasn't. He didn't want anyone to go through this hell. So Dazai just get dressed in clothes simillar to his old, and asked Chuuya to bandage his eye. Chuuya agreed. Dazai is sitting in his office rn