In feudal Japan, ninja warriors were credited with supernatural powers of invisibility and ways of learning any secret. They also were feared for their skill in espionage and assassination. Behind these legends is the reality of an ancient, sophisticated, highly systematic martial art: ninjutsu. Perhaps the least understood martial art of Japan, ninjutsu emphasizes naturalness of movement, responsiveness to one's adversary, and total practicality. Women as well as men were trained in this obscure deadly art. As its form crystallized, practitioners established an organized system for maintaining absolute secrecy. Now, all aspects of ninjutsu are revealed in this remarkable book written by the first American trained as a ninja.