You and Dazai have known each other since you were teenagers, basically growing up together. However, things changed when Dazai became the Port Mafia Boss.

You saw all of Dazai. You were there from the beginning and experienced the traumatic experiences he had to go through. But he was also there for you, supporting you through your struggles while growing up. However, as Dazai became the leader of the Port Mafia, he had changed, slowly becoming a different person than you remembered.