A PATH THAT COULD HAVE BEEN… In the world of Bungo Stray Dogs, Ryuunosuke Akutagawa is infamous for being one of the Port Mafia’s most dangerous members. But what if his past had turned out differently...? When Dazai decides to pass on taking in an orphaned Akutagawa, the boy winds up being recruited by none other than the Armed Detective Agency! With his sister still in the Mafia’s clutches, Akutagawa will stop at nothing to take her back. However, standing in his way is the Port Mafia’s top enforcer—the White Reaper, Atsushi Nakajima. As darkness and light face off in a twisted mirror of what could have been, a new tale begins to take shape…

妹を取り戻す為、芥川に課せられた第一の試練。それは──田植え!? 妹を捜し出す為の条件として、探偵社の面々から個別に提示された条件を達成するように告げられた芥川。早速、探偵社の一員・宮沢賢治が提示した「田植え」に取り組むことにな

武装探偵社VSポートマフィア、遂に全面衝突──!! 捜し求めていた妹・銀がポートマフィアのアジトにいることを知った芥川は、仲間の制止を振り切り、単身で正面から乗り込んでいく。遂に四年半越しの再会が果たされるかと思いきや……。

Akutagawa and Atsushi devote everything they’ve got to an explosive final confrontation. After a desperate battle for the things most important to them, they both learn the real “truth” of this world… The thrilling spin-off of Bungo Stray Dogs comes to a grand conclusion!