Once every 30 years, a member of Hime lineage took on the mantle of princess to become the Hayagami. However, recent records indicate that no female descendants have surfaced apart from 15-year-old Arata. To keep the tradition alive, Arata masquerades as a female aspirant while awaiting a suitable successor. The situation becomes dire when Kokuri-hime, the reigning princess, gets murdered, and her loyal protector, the Shinshou, turns its attention towards Arata's life. With the 12 Kannagi on his back, Arata goes on the lam as he faces accusations for the heinous crime while becoming the primary target of the Imperial Court.