I thought of a crazy idea - well, not as crazy as aliens versus ninjas. The son of a disgraced ninja returns to his father's clan to clear his name. At the same time, the clan is preparing to send another team to fight in the name of the Emperor for the glory of Japan. The year is 1942. The Philippines and southeast Asia have fallen, China is in ruins, Austrailia is threatened, there is fighting in Guadalcanal and the Aleutians, and Pearl Harbor is still fresh in minds of those living in Hawaii and along the west coast of America. In each of these, ninjas had a hand. Japanese-Americans, regardless of immigration status are living in concentration camps in the deserts of eastern California and western Arizona and Nevada, or else are reviled as potential traitors. However, with the threat of ninja infiltration of North America in the back of everyone's mind, Japanese-Americans with ninja training have the chance to prove thier good citizenship. Our fallen ninja settled in San Francisco and started a family after he (or she) was exiled from the clan, and now resides in one of the concentration camps.
Think of this as ninja versus the original GI Joe (not those goons that fight Cobra Commander and give public service announcements to kids) with the added bonus of conflict of loyalties. Perhaps even a three way battle between ninjas, the US military, and loyal US citizens of Japanese descent.
