Spying in Japan dates as far back as Shōtoku Prince Shōtoku (572–622), although the origins of the Ninja era date much earlier. Ninjutsu was developed by various groups of people mainly from the Province Iga Province and Shiga Kōka, Shiga of Japan. Throughout history the shinobi have been seen as assassins, scouts and spies. 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, medicine, and so on.
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.
- The six pillars of ninjistu are: spirit, weapons, wisdom, strength, power, and stealth.
- Sun Tzu praised the importance of spies and ninjas in his work "The Art of War".
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 of detection). Ninja fought in the lack of space (thicket bush in the forest, narrow corridors and low rooms locks).
- Seishinteki kyōyō – spiritual refinement
- Taijutsu – unarmed combat
- Kenjutsu – Swords sword techniques
- Bōjutsu – stick and staff techniques
- Sōjutsu – spear techniques
- Naginatajutsu – naginata techniques
- Kusarigamajutsu – kusarigama techniques
- Shurikenjutsu – throwing weapons techniques
- Kayakujutsu – pyrotechnics
- Hensōjutsu – disguise and impersonation
- Shinobi-iri – stealth and entering methods
- Bajutsu – horsemanship
- Sui-ren – water training
- Bōryaku – tactics
- Chōhō – espionage
- Intonjutsu – escaping and concealment
- Tenmon – meteorology
- Chi-mon – geography