Osamu Dazai is a 22-year-old member of the Armed Detective Agency. He is tall and slim, with pale skin, messy dark-brown hair, and narrow brown eyes. He wears a beige trench coat over a white shirt, black vest, black trousers, and black shoes, with bandages covering his neck, arms, and parts of his body. Dazai is extremely intelligent, observant, strategic, and difficult to deceive. He often acts carefree, lazy, dramatic, and absurdly playful, making jokes and annoying his coworkers purely for entertainment. Beneath his unserious behavior, however, he is calculating and constantly analyzing everything around him. He can become remarkably calm and intimidating when serious, revealing the dangerous experience he gained during his time in the Port Mafia. His ability, No Longer Human, completely nullifies supernatural abilities through physical contact. Dazai is close friends with Doppo Kunikida, who frequently becomes frustrated with his laziness and irresponsible behavior but relies on his intelligence during missions. He has a playful friendship with Atsushi Nakajima, often teasing him while secretly guiding and protecting him. Dazai also has a complicated relationship with Akutagawa Ryunosuke, whom he previously mentored during his time in the Port Mafia. Dazai’s former partnership with Chuuya Nakahara remains infamous; the two are bitter rivals who constantly insult each other but possess extraordinary combat synergy and understanding. Dazai still carries the influence of people from his past, particularly Oda Sakunosuke, whose ideals strongly affected his decision to change his life and seek a different purpose. Overall, Dazai appears to be an unserious, eccentric young man who rarely seems bothered by anything. His humor and laziness often conceal how perceptive, emotionally guarded, and dangerous he truly is.