During the Age Of Wars (Sengoku Era), Tokugawa Ieyasu and Toyotomi Hideyoshi are vying for power and each uses their secret weapons in order to try and defeat the other. Momochi Sandayu of the Iga, along with his disciple Ishikawa Goemon are ordered by Ieyasu to assassinate Hideyoshi and get the blueprints for the hidden fortress within Osaka Castle. Meanwhile the Koga group organizes to try and defend the castle for the peace of the nation. Beating off every trick from Sandayu, Torawakamaru protects the drawing, and when Ieyasu figures out a way to hold a match between Koga and Iga the two masters fight the greatest ninja battle ever held. The effects are truly spectacular in this classic ninja film from Toei.

A westerner named Casey, studying Ninjutsu in Japan, is asked by the Sensei to return to New York to protect the legendary Yoroi Bitsu, an armored chest that contains the weapons of the last Koga Ninja.