Basilisk: The Ouka Ninja Scrolls

The story takes place in the year 1614. Two ninja clans, Tsubagakure of the Iga and Manjidani of Kouga, battle each other to determine which grandson of Tokugawa Ieyasu will become the next shogun. The deadly competition between 10 elite ninja from each clan unleashes a centuries-old hatred that threatens to destroy all hope for peace between them.