文豪ストレイドッグス 第2シーズン

This second season opens four years in the past, when Osamu Dazai was still the youngest executive of the Port Mafia. Alongside his friend Oda Sakunosuke, a low-ranking mafioso who refuses to kill, Dazai frequents a bar where the third member of their circle, Ango Sakaguchi, vanishes without warning. As Dazai and Oda investigate the disappearance, the Port Mafia's war with the rival organization Mimic escalates, and the events of this 'Dark Era' set the stage for Dazai's eventual defection to the Armed Detective Agency.