Osamu Dazai, a member of the Armed Detective Agency and former Port Mafia executive, possesses the Ability "No Longer Human," allowing him to nullify others' abilities through skin contact. Tall and slim, he sports dark brown hair and eyes, often seen in a sand-coloured trench coat over a black vest and striped dress shirt, with bandages covering his body. Despite his mysterious demeanour, Dazai's true intentions remain concealed, known only to a few like his late friend Sakunosuke Oda.