Crows

Harumichi Bouya transfers to Suzuran High mid-year, but this isn't just any school, it is know as the Crows School where the rotten of the rotten students go to. Bouya becomes the number one fighter in the school and in doing so he sets off a chain of events of high school gang warfare in the area. Crows is the prequel of the manga "Worst", and it a story occurring in Suzuran two years before the story of "Worst." (Source: AniList)