The era when Samurai and Ninja existed in Japan. Rikka Isurugi was born and raised in a Ninja clan secluded from society. She soon meets Miya, a girl with a mysterious power, who is found lost in the mountains. As Rikka is concerned that someone is pursuing Miya, she also asks the head the of Isurugi Ninja Clan for permission to avenger her father's death. Soon Rikka faces danger with the attack of the Negoro group but…

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.