Tokyo卍Revengers: Baji Keisuke kara no Tegami

The Tokyo Manji motorcycle gang has carved out a reputation as the toughest band of delinquents in Tokyo. No matter who stands against them in a fight, no matter how bad the odds, Toman always emerges undefeated. Yet its members all carry the scars of "Bloody Halloween," the night when a showdown with a rival gang saw their First Division Captain, Keisuke Baji, get senselessly murdered. Months later, vice-captain Chifuyu Matsuno is still struggling to make sense of what happened. When he receives a letter from Keisuke Baji–written on the day of his death–it stirs up memories of all their years together...

(Source: Seven Seas Entertainment)