Origin of the NinjaThe ninja are, by nature, a mysterious and fascinating group. Popular culture and movies have slowly twisted this ancient warrior into a legend, so keep reading to find out the real facts!While the origin of the ninja is unclear, the Japanese legend claims that the original ninja descended from a demon. One of the more realistic theories is that the practice began around 600-900 A.D. when a prince hired Otomono Sahito as a spy. The ninja combined the philosophy of guerrilla warfare with a specialized training method called shugendo. Eventually, the Japanese regions of Iga and Koka became the two main centers of ninja training.