Haruka Sakura arrives in the town of Makochi determined to conquer Furin High School, only to discover that under top leader Hajime Umemiya, Furin has abandoned standard gang delinquency to form "Bofurin," a neighborhood defense force. Sakura enters the school and is bewildered when classmates like Akihiko Nirei, Hayato Suo, and Kyotaro Sugishita welcome him with goodwill. However, an antagonistic encounter quickly sparks a turf war with Shishitoren, a neighboring gang led by Choji Tomiyama that operates on absolute survival of the fittest. To prevent street casualties, Umemiya arranges five one-on-one cage matches in Shishitoren's territory. After Sugishita, Suo, and Heavenly King Toma Hiiragi win their bouts, Sakura faces Shishitoren’s vice-captain, Jo Togame. Sakura breaks through Togame's bitter fighting style, forcing him to confront how Shishitoren lost its joy, and claims victory. In the final match, Umemiya absorbs Tomiyama’s attacks, teaching him that leading through fear only creates a desolate summit. Tomiyama reconciles with Togame, restoring peace, and Sakura is formally appointed First-Year Grade Captain.
In the second season, Sakura faces the trials of leadership when classmate Anzai is targeted by Keel, an illicit syndicate dealing in extortion and weapons. Keel forces Sakura, Nirei, Suo, and allies Mitsuki Kiryu and Taiga Tsugeura into guerrilla street clashes. Furin's upper echelon mobilizes, bringing Four Heavenly King Tasuku Tsubakino into combat to crush Keel's leadership. As external factions like Gravel attempt to exploit Makochi's borders, Sakura must coordinate his class while realizing that leadership means bearing responsibility for his peers' safety.
In the series finale, Sakura coordinates his grade in an all-out town defense alongside Furin's senior guard. Sakura no longer fights as an isolated wanderer seeking validation, but as the trusted core of Bofurin's frontline. The series concludes with Sakura standing alongside Umemiya on Furin's rooftop garden: while he still aspires to take the top, he now understands that the top is not a throne of conquest, but a commitment to protect the town and his brothers beneath the shelter of the wind.