The historical epic centers on Shichika Yasuri, the seventh generational head of the Kyotō-ryū school of martial arts in medieval Japan. He and his older sister Nanami live on an isolated island, until a military advisor named Togame tells him of the final 12 swords forged by a legendary swordsmith. At Togame's bidding, Shichika embarks on a journey to find all 12 of the swords.