Jamie and Yoshi are late twentieth century members of the Funakoshi ninja clan who were trained by Yoshi's uncle, Tanemura Funakoshi. When the Waruiyatsu, a sinister clan with an ancient grudge, attack Jamie's high school and hold his classmates hostage in an effort to bring Tanemura and his two students into the open, Jamie and his clan sister are forced to attempt a rescue.
Going along are a close group of friends, each with his own interest in the fighting arts. From Dave, whose muscle-bound frame and love of a good scuffle are overshadowed by his cheerful personality and kind heart, to Buster, whose Bible is his greatest weapon, each of their friends has a loyalty to them and each other that is stronger than the Waruiyatsu can ever fathom.