In an alternate universe of Bungo Stray Dogs, this “what-if” narrative envisions a scenario where Atsushi Nakajima is part of the Port Mafia, while Ryūnosuke Akutagawa belongs to the Armed Detective Agency, reversing their usual roles. The plot centers on Ryūnosuke Akutagawa, who is determined to seek vengeance against a mysterious man in black to save his sister. Just as he is on the brink of starvation, a member of the Armed Detective Agency comes to his aid.