While training to become a true bushi, Sei, a girl disguised as a boy, asks assistant vice captain Saito for help with a skill, and he soon becomes confused by his romantic feelings toward someone he thinks is male.

Akesato the courtesan has been instrumental in hiding the fact that Sei is a girl by pretending to be "his" lover, but Yamanami, another member of the Shinsengumi, has fallen madly in love with Akesato.

Sei, hoping to find a spot on Soji's Shinsengumi team, is instead chosen as personal assistant to Yamanami who wants to keep her safe, and though she works diligently at her duties, her true skills as a samurai show themselves when Soji and his men are attacked.