Takeshi Chimatsuri, a 16-year-old student in Arashiyama-machi, bears the legacy of his late father Arashiyama Raizou—a celebrated samurai who secured the family’s heirloom dagger by defeating a rival ninja in single combat. His family, including mother Shizuka, older sister Asagi, and younger sister Ayako, anchors his resolve to honor their name. Embracing samurai traditions, Takeshi dons historical garb and carries his blade daily, a commitment shadowed by an old feud.

The Toki twins, Kagiri and Akari, descendants of Raizou’s defeated foe, infiltrate his school to reclaim the dagger. Their strategy hinges on exploiting Takeshi’s debilitating phobia of female nudity, triggering panic attacks that cripple his focus. Determined to overcome this weakness, he trains under the guidance of classmates Atsuko and Torai, alongside instructor Miss Ayatsugi, confronting his fear through gradual exposure.

Though childhood ties bind Takeshi to the Toki sisters, their past remains shrouded. His routine—a fusion of martial discipline and teenage academics—crumbles under their relentless schemes, thrusting him into clashes testing both sword arm and psyche. Amidst schoolyard normalcy and ancestral duty, Takeshi walks a razor’s edge, where every encounter could spell dishonor or hard-won growth.