In 1614, the long-standing truce between the Kouga and Iga ninja clans is broken when each side is ordered to select ten warriors for a deadly contest that will determine the succession of the Tokugawa shogunate. Caught between the rival clans are Gennosuke of Kouga and Oboro of Iga, heirs who had hoped their marriage would finally bring peace between their people.

Designed to select the successor to the Tokugawa family, a gruesome battle once promised a thousand-year reign to the winning clan. Amidst the bloodshed, betrothed lovers Oboro and Gennosuke were forced to take sides. Only ten years have passed and once again the clans of Kouga and Iga are poised to fight. But this time, a new generation stands at the forefront.