Crows

Harumichi Bouya transfers into Suzuran All-Boys High School, a school so notorious for its uniformed delinquents that locals call them the Crows. What begins as one transfer student’s casual brawls becomes an escalating war between factions, gangs, and legends, with bonds forged in violence and loyalty pushed past the breaking point.

(Source: Kodama Tales)

Crows is the prequel of the manga "Worst", and it a story occurring in Suzuran two years before the story of "Worst."