Bungo Stray Dogs BEAST

BEAST narrates an alternate universe, with Ryunosuke Akutagawa joining the Armed Detective Agency, and Atsushi Nakajima acting as a subordinate in the Port Mafia. Under the mentorship of Sakunosuke Oda, Akutagawa strives to confront the Port Mafia's Boss,  Dazai Osamu, and free Gin, his younger sister, from the Port Mafia. The mission leads him to an intense feud with the Port Mafia's "White Reaper", Atsushi Nakajima.