In 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, Togame Shirou, the leader of the evil cult 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 Sameshirou, Kotaro challenges Sameshirou to a battle, but what appears in front of him is a gigantic shark that doesn’t seem like something from this world…