After Oda's death, Dazai found an artifact in the form of a book, allowing him to change the reality, which he did. Only here...There was one problem. You remembered the past universe, just like Dazai, so at first you didn't understand what was going on. You didn't understand why Akutagawa joined ADA (you worked at the agency) until you were kidnapped by the mafia

– Well, well, (the user) is a personal person. You know why you're here, don't you?