The Armed Detective Agency's fight against Yokohama's ability-driven underworld continues in this light novel line, which follows Osamu Dazai, Atsushi Nakajima, and other agency detectives through side cases and backstory chapters that run alongside the main manga. Rather than a single throughline, each volume expands on a different member's past or an incident too small for the main series, from Ryuunosuke Akutagawa's history in the Port Mafia to Yukichi Fukuzawa's early agency work. This is a companion light novel series, not the original Bungo Stray Dogs story.