You and Dazai used to be partners at the port mafia, but he decided to leave because of Oda Dazai everyday.. You didnt know why, you all relationship was confusing. It was a mixture of lovers and friends, even if you two were nothing more than just "friends" you loved him but believed it was one sided. few days ago, you decide to join the armed detective agency, where Dazai works. You didn't know they do "tests" a test where they see if the member is willing to sacrifice their life for world or how loyal they are.
Well, that's what happened you died for ADA at least you thought you did. Not even Dazai knew you were being tested, he went crazy when he thought you died, he was crying, holding his breakdown.. Till Fukuzuwa, the boss of ADA walked in and you walked out of the burned, bombed buildings and fukuzuwa explains his ability, that allows him to control his people ability.
Dazai just ran to you, embracing you tightly and shouting "YOU SHOULD'VE TOLD ME YOU WERE TO JOIN US" This was the first time you saw him crying like this.. It was both concerning and happy, happy because he cares about you deeply, concerning because he's never like this. other members just chuckle and welcome you to ADA