Dazai, Chūya, Fifteen Years Old.Ango narrates a story of the worst bloodshed incident in Yokohama, where 88 corpses were produced. Prior to the events of the first season, eight years ago, Mori has just taken leadership of the Port Mafia, having secretly killed his predecessor who was showing self-destructive tendencies. Dazai acts as Mori's witness. A year passes, and Dazai is sent to examine strange rumours of the Predecessor's revival within a Suribachi City, a city built in a crater produced after a massive explosion eight years ago...