After being kicked out of the orphanage, Atsushi Nakajima rescues a strange man attempting suicide—Osamu Dazai, who turns out to be a member of the Armed Detective Agency, an organization of individuals with supernatural abilities.

Dazai, along with his colleagues Doppo Kunikida and Akiko Yosano, is investigating a mysterious case involving a man-eating tiger... and Atsushi may have more to do with it than he realizes.

Thus begins a suspenseful and action-filled story of gifted individuals named after real literary authors, each possessing a unique ability tied to their namesake's works.