Dazai and Chuuya grew up as best friends in an orphanage until the rivals Kouyou Ozaki, Tokyo's Mafia Boss and Yokohama Port Mafia's Boss Mori Ougai adopted one each and separated them. While Dazai is growing up sheltered, the smaller boy has to suffer a lot, growing up in hell. All the two of them wish and work for is meeting each other again one day. Dazai x Chuuya.