中島敦撞見太宰治再度意圖自殺後，終於受不了了。太宰介紹他加入武裝偵探社。

國木田與太宰調查橫濱的一連串失蹤案。駭客田口深信他們都跟神出鬼沒的「蒼之使徒」有所牽連。

The Port Mafia's council of five top executives has decreed that Mimic must be annihilated. In the ensuing battle, Odasaku has a fateful encounter with Gide, the leader of Mimic, who makes a cryptic prophecy. Night falls, and the usual bar now awaits Dazai, Odasaku and Ango...

Atsushi and Akutagawa fail to call off the Moby Dick's descent. They search desperately for other ways to protect Yokohama.