Eikichi Onizuka, the legendary former biker and unorthodox teacher, arrives in the small, economically depressed rural town of Horobonai in northern Japan on his motorcycle. He has been hired as a substitute teacher at a local high school, a job he takes after his wallet is stolen. The town has been in a downward spiral since the closure of its Canadian-themed amusement park, leaving its teenagers, including the students of Class 2C, in a state of deep apathy and despair.

Almost immediately, Onizuka intervenes in two separate suicide attempts by students: a boy named Raku Ichikawa lying on train tracks and a girl named Ayano Katsuragi standing on the school roof. Ayano is the daughter of the powerful and wealthy school chairman, who plans to demolish the old school and the abandoned theme park to build a waste treatment facility. Onizuka is assigned to Class 2C, where both Raku and Ayano are students, and he moves in with Raku's family, who run a local farm. His outrageous teaching methods include forcing Raku to fight a bully while the class places bets, a stunt that inadvertently boosts Raku's social standing and reveals his hidden crush on Ayano.

Complicating matters, a tenacious newspaper reporter named Kaoru Kitajima and her photographer Ishiyama arrive in Horobonai. Kaoru is pursuing a serial criminal and finds Onizuka's wallet at a crime scene, leading her to believe the loud-mouthed teacher is the culprit. She stalks him around town, hoping for a major scoop, while Onizuka, oblivious to her suspicion, is focused on preventing Ayano from being sent away to a finishing school in London. As the chairman accelerates his demolition plans and the police surround Onizuka, mistaking him for the real criminal, Onizuka stages a spectacular rebellion. He pulls Ayano off a departing train, leads the police on a chaotic chase, and finally holds an impromptu class in the condemned old school building with the entire student body.

In the climax, Onizuka forces Raku to confess his feelings to Ayano, and the town’s broken clock tower begins to chime again, symbolizing hope and renewal. Just as the police are about to arrest Onizuka, his old friend Seiji, the actual serial criminal who has been hiding in town, reveals himself for the sake of notoriety. With the real criminal apprehended, the town rallies behind Onizuka. Kaoru writes an article clearing his name, leading to a promotion. The plan for the waste treatment facility is canceled, and Onizuka rides out of Horobonai on his repaired motorcycle, having once again proven that his unorthodox, heartfelt approach can reach students no conventional teacher could.