While there are several styles of modern ninjutsu, the historical lineage of these styles is disputed. Some schools and masters claim to be the only legitimate heir of the art, but ninjutsu is not centralized like modernized martial arts such as judo or karate. Togakure-ryū claims to be the oldest recorded form of ninjutsu, and claims to date past the 1500s.
Spying in Japan dates as far back as Prince Shōtoku (572–622), although the origins of the Ninja date much earlier. According to Shoninki, the first open usage of ninjutsu during a military campaign was in the Gempei War, when Minamoto no Kuro Yoshitsune chose warriors to serve as shinobi during a battle; this manuscript goes on to say that, during the Kenmu era, Kusonoki Masashige used ninjutsu frequently. According to footnotes in this manuscript, the Gempei war lasted from 1180 to 1185, and the Kenmu Restoration occurred between 1333 and 1336. Ninjutsu was developed by groups of people mainly from the Iga Province and Kōka, Shiga of Japan. Throughout history the shinobi have been seen as assassins, scouts and spies who where hired mostly by territorial lords known as the Daimyo. They conducted operations that the samurai where forbidden to partake in. They are mainly noted for their use of stealth and deception. Throughout history many different schools (ryū) have taught their unique versions of ninjutsu. An example of these is the Togakure-ryū. This ryū was developed after a defeated samurai warrior called Daisuke Togakure escaped to the region of Iga. Later he came in contact with the warrior-monk Kain Doshi who taught him a new way of viewing life and the means of survival (ninjutsu).
Ninjutsu was developed as a collection of fundamental survivalist techniques in the warring state of feudal Japan. The ninja used their art to ensure their survival in a time of violent political turmoil. Ninjutsu included methods of gathering information, and techniques of non-detection, avoidance, and misdirection. Ninjutsu can also involve training in free running, disguise, escape, concealment, archery, and medicine.
Skills relating to espionage and assassination were highly useful to warring factions in feudal Japan. These persons were literally called "non-humans" (非人,hinin?). At some point the skills of espionage became known collectively as ninjutsu, and the people who specialized in these tasks were called shinobi no mono.
Ninja jūhakkei was often studied along with Bugei Jūhappan (the "eighteen samurai fighting art skills"). Though some are used in the same way by both samurai and ninja, other techniques were used differently by the two groups (ninja martial arts was adaptation to surprise attacks at night, in the back or ambush and at espionage to stun the enemy for escape in case detection). Ninja fought in the lack of space (thicket bush in the forest, narrow corridors and low rooms locks).
The name of the discipline of taijutsu(体術?), literally means "body skill" or "body art". Historically, the word taijutsu is often (in Japan) used interchangeably with jujutsu (as well as many other terms) to refer to a range of grappling skills. The term is also used in the martial art of aikido to distinguish the unarmed fighting techniques from other (e.g., stick fighting) techniques. In ninjutsu, especially since the emergence of the ninja movie genre in the '80s, it is also used to avoid the undesired bravado of explicitly referring to ninja combat techniques.
Kusari-fundo, also known as manriki or manriki-gusari - a chain and weight weapon.
Kakute - rings resembling modern wedding bands with concealed, often poison-tipped spines, typically worn by kunoichi and enabling ninja to quietly strangle enemies with the pointed ends against the neck or throat
Shobo - a jabbing or piercing weapon, similar in shape to kubotan and yawara, but often featuring a center grip ring
Shuriken - various small hand held weapons including "throwing stars" that could be used to stab, slash or they could be thrown
^Masazumi, Natori, translated by Editions Albin Michel and Jon E. Graham. "Shoninki: the Secret Teachings of the Ninja; the 17th-Century Manual on the Art of Concealment", English Translation Copyright 2010 by Inner Trditions International.
DiMarzio, Daniel. A Story of Life, Fate, and Finding the Lost Art of Koka Ninjutsu in Japan, 2008. ISBN 978-1-4357-1208-9
Bertrand, John. "Techniques that made ninjas feared in 15th-century Japan still set the standard for covert ops", Military History 23(1), March 2006, pp. 12–19. Retrieved on July 11, 2008 from Academic Search Premier database.
Hayes, Stephen K. and Masaaki Hatsumi. Secrets from the Ninja Grandmaster (Rev. Ed.), 2003. Boulder, Colorado; Paladin Press.
Zoughari, Kacem. The Ninja: Ancient Shadow Warriors of Japan, Tuttle Publishing, 2010. ISBN 0-8048-3927-1