The battle for succession that continued for three generations of shogun in the Keich˘ era culminated in a gruesome battle of ninja arts between the K˘ga and Iga clans. Amidst a rain of flower petals, a man and woman who had decided to live for love were separated once again. However, it is said that by the hand of Hattori Hanzo's adopted son, Ky˘hachir˘, these two lovers were given life again and left two mementos behind.
These children, born with a destiny of their own, were called Hachir˘ K˘ga and Hibiki Iga. The former had eyes like his father's, and the latter had eyes like her mother's. It is now the Kan'ei era, and the land is at peace. As ninjas begin to disappear into the shadows after being deemed unnecessary, The Kouga and Iga clans ask a favor of Hachir˘ and Hibiki in hopes of reinforcing their foundations.