The story begins 800 years ago, in feudal Japan. Seeking autonomy from the oppressive class system of the time, a few citizens fled into the mountainous regions of Iga and Kōga. There they developed ninjitsu, a stealthy martial art perhaps inspired by Sun Tzu's "The Art of War". Over a period of centuries, they refined their art in secluded camps. Students trained and practiced the art from birth, playing children's games designed to impart expertise in unarmed combat, swordplay, weaponry, camouflage, escape, and evasion. Ninjitsu was also designed to encourage spiritual growth by pushing oneself physically and mentally beyond normal human limits. The ninja were experts in espionage and assassination, and offered their specialized services to samurai warlords and others who could afford them.