Fuu Kasumi, a bumbling young waitress, lives a tranquil existence at a modest teahouse until she clumsily spills a drink on a patron, triggering harassment from a gang of samurai. In a moment of panic, she summons Mugen, another samurai present in the establishment, who swiftly neutralizes the aggressors using a unique combat style blending breakdancing with martial arts. Mugen subsequently goads Jin, a reserved and highly skilled ronin renowned for his traditional swordsmanship, sparking a violent clash that demolishes the teahouse and accidentally results in the death of the magistrate's son.
Apprehended and condemned to death for their actions, Mugen and Jin are liberated by Fuu, who employs them as her protectors. Having lost her home, Fuu resolves to hunt down a samurai who carries the scent of sunflowers, convincing the two former warriors to accompany her on this mission. Though initially hesitant, they consent to aid her. The trio sets off on a journey brimming with action, comedy, and fierce sword battles, all underscored by a distinctive hip-hop soundtrack. Their travels unfold in an alternate Edo Period Japan, where this unconventional group seeks to solve the mystery of the sunflower-scented samurai while striving to prevent Mugen and Jin from coming to blows with one another.