The time is the Edo period. The slaughtered corpses of villagers are found on the beach of remote Okitsu village. In order to obtain the power of immortality, Koshiro Mizuchi , the leader of the heresy group Koumashu, uses magic to manipulate sharks to forcibly steal pearls from the villagers. Frustrated by this situation, the village chief goes to see Kotaro Shiozaki, a bodyguard at a temple on the outskirts of the village, to ask for help. Kotaro accepts the job with a reward, but his path is blocked by a female ninja named Kikuma. Along with Shinsuke, who resists the village chief's attempt to sacrifice a villager, Sayo, to Koshiro, Kotaro challenges Koshiro to a battle, but what appears in front of him is a gigantic shark that cannot be thought of as something of this world. . The ultimate battle between ninjas and sharks will finally come true! Which one will survive! !