Kenka no Gokui 1 (2008)

Haru Urara (Hiroaki Ogasawara), a transfer student, arrives at Kyokuto Industrial High, a school infamous as a den of delinquents known as “Kiwakou.”
Mocked for his name, Haru snaps and goes on a rampage on his very first day, wiping out his class and instantly becoming notorious.
Targeted by delinquents across the school, Haru charges headfirst into a life of nonstop fights alongside his powerful best friend Shingo.
But things take an unexpected turn when Haru falls for Kana, a girl he saves by chance—just as mysterious assaults leave several Kiwakou students critically injured…