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…

Haru and Shingo’s days remain filled with constant brawls. When a new transfer student arrives, Haru braces for a rival—only to discover the newcomer is Kana’s older brother. While Haru awkwardly tries to get closer to Kana, disaster strikes: she is kidnapped by students from a rival school. United by rage, Haru and the others charge in for a rescue—only to face an unseen threat waiting for them.

Rumors spread about Haru, the feared brawler, as challengers line up to test him. One day, rival school Aokou is wiped out overnight. The culprit: Red Tengu, the strongest biker gang around. Soon after, Red Tengu’s charismatic leader Tesshin personally appears at Kiwakō. “Tomorrow. At the riverbank.” School pride, team loyalty, and manhood collide in a brutal showdown that stains the blue sky red.

Expecting another enemy, Haru is instead approached by Sho, a bespectacled honor student from an elite prep school. Sho, partnered with the ruthless Kenshin, is running an underground fight ring called “Fight Club” and tries to recruit Haru. Haru refuses to turn fighting into business—but the Fight Club targets his friends to force his hand. The club leader is beaten senseless, Shingo is sent to intensive care, and the ring ignites with delinquent pride on the line.

As graduation approaches, Tatsuya—the right-hand man of Kiwakou’s strongest fighter Momo—leaves school. Spring draws near, but Haru and the first-years live only for today’s fights. Their next opponent: Gakki, the strongest fighter from Rangaku High and Momo’s lifelong rival. A long-standing ceasefire shatters as the two schools clash head-on in a 4-on-4 one-on-one battle, pride against pride.

After fighting every single day, Haru and Shingo have grown absurdly strong. Yet stronger enemies keep coming—this time from Byakuya Academy, whose elite unit “Brother Scorpion” launches a full-scale assault. Overwhelmed by numbers, Kiwakō faces its greatest crisis. Momo entrusts everything to Haru, marking a generational shift as the ultimate school war begins. In the chaos of battle, Haru is forced to discover what strength truly means.