A member of the Armed Detective Agency who takes Atsushi under his wing, Dazai is known for being a "suicide maniac" because he wishes to commit suicide and die comfortably one day with a beautiful woman. Under his carefree and relaxed demeanor, however, Dazai is extremely cunning, intelligent, and also a funny guy.

Dazai is a young man with mildly wavy, short, dark brown hair and narrow dark brown eyes. His bangs frame his face, while some are gathered at the center of his forehead.