In 1863, a period marked by violent social upheaval, samurai from all backgrounds converge on Kyoto, hoping to join the Mibu-Roshi—a group of warriors bound by their unwavering loyalty to the Shogunate. Eventually, this faction would evolve into one of the most renowned (and famous) movements in Japanese history: the Shinsengumi. Amidst this intense atmosphere enters Seizaburou Kamiya, a young aspiring warrior who, despite his lack of combat experience, burns with a fierce desire to assist the Mibu-Roshi in their mission and to avenge his family, who were wrongfully murdered. Souji Okita, one of the Mibu-Roshi's most talented (yet immature) swordsmen, agrees to take Seizaburou under his wing. What no one suspects, least of all Souji, is that Seizaburou is actually a girl named Sei Tominaga in disguise!