In order to save Paris from an international bloodbath, a grieving scientist is forced to face her tragic past when a giant shark appears in the Seine.

A mafia drug lord has unleashed a new, highly addictive stimulant on the streets called HT25, derived from sharks held captive in a secret lab, and which causes monstrous side effects. After an explosion and leak at the lab, an army of mutated, bloodthirsty sharks and other creatures are set loose on the world.

In the Edo period, at the remote village of Okitsu, the evil cult leader Koushirou uses ninjutsu to bewitch sharks and forces them to attack local pearl divers so the cult can steal the pearls from their mangled corpses. Desperate for help, the village chief hires Kotaro Shiozaki, a guard at a nearby temple, but Kotaro soon finds his path blocked by lady ninja Kikuma and a gigantic shark that doesn't seem like something from this world.