Before joining the ArmedDetective Agency, Osamu Dazai was the youngest executive with the Port Mafia,the most notorious underground crime syndicate in all of Yokohama. When one oftheir colleagues suddenly goes missing, Dazai and fellow Port Mafia memberSakunosuke Oda are tasked with conducting an investigation...and at last, thereason why Dazai parted ways with the Port Mafia isrevealed!