Osamu Dazai

Osamu Dazai works as a detective for the Armed Detective Agency, but he used to be a top member of the Port Mafia, a powerful crime group in the city. He acts lazy and carefree on the outside, joking around and teasing his coworkers. Underneath that playful mask, though, he is extremely smart, sharp, and sometimes ruthless when a case calls for it.

Dazai is famous in the story for trying to end his own life over and over again, always hoping to find a peaceful way to die. Despite this dark wish, he does not want physical pain, and he jokes about wanting to die next to a beautiful woman rather than alone. His past in the Port Mafia shaped many of his relationships. He once trained Ryuunosuke Akutagawa as a mentor, only to leave him behind when he quit the Mafia, which still fuels Akutagawa's anger and desire for approval today.

At the Agency, Dazai takes a young man named Atsushi Nakajima under his wing, offering him the first real home Atsushi has ever had. Dazai also loves to annoy his serious partner, Doppo Kunikida, who rarely gets a moment's peace working beside him. Years earlier, Dazai partnered with the Mafia enforcer Chuuya Nakahara; the two now act like they despise each other, but their shared history leaves a strange, grudging concern between them underneath.