At the dawn of Japan's Azuchi-Momoyama period (the late 16th century) two rival ninja clans, the Iga Tsubagakure and Kouga Manjidani, are engaged in a bitter blood feud that has spanned for centuries.
In order to solve the problem before it spirals out of control, Ieyasu orders the no hostilities pact between Kouga and Iga canceled and promptly commands each clan to send 10 of their best ninja to enter a ruthless and bloody competition of kill or be killed.