In Japan, the home of Cho Osaki is attacked by an army of a rival ninja clan, resulting in the slaughter of his entire family except for his mother and his younger son, Kane. When Cho arrives at his estate and discovers the carnage, the ninjas attempt to kill him as well, but Cho, a highly skilled ninja himself, avenges his family and kills the attacking ninjas. Afterwards, however, he swears off being a ninja forever and moves with his son and mother to America, where he opens an Oriental art gallery with the help of his American business partner and friend, Braden, and his assistant Cathy.