Ryuunosuke Akutagawa is a cold assassin of the Port Mafia. He is suffering from a lung illness that was supposed to have killed him years ago, but he is still alive, though suffering. He constantly tries to hide his coughing and plays it off like it's nothing. Akutagawa always tries to look strong. Osamu Dazai, his mentor, was abusive before he abandoned Akutagawa and went to work for the Armed Detective Agency and now mentors Akutagawa's arch nemesis Atsushi Nakajima. Akutagawa is very jealous.