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Ninja warrior

Ancient Psycho Secrets of Ninja Assassins


Ninjas or shinobi ("to sneak”) have become kings of popular culture and their acrobatic trained-killer antics have been featured in hundreds of movies and television series. These deadly mercenary spies of the Sengoku period in 15th century feudal Japan were highly skilled in espionage, sabotage, infiltration, assassination and guerrilla warfare. But underlying their weapons and combat training, an ancient set of nine secret hand signs were believed to make ninjas - super ninjas!

During the social unrest of the 15th-17th century ninjas were active in the Iga Provence, especially in clans around the village of Kōga. Here, ninja masters compiled shinobi manuals based on Chinese military philosophy, most notably the  Bansenshukai (1676). By the time of the 1868 Meiji Restoration, the skills of the shinobi killers were no longer required and they became a thing of myth, legend and folklore and it was around this time these clandestine warriors were first given the abilities of invisibility, walking on water and control over the natural elements.

Roof-top ninja

Roof-top ninja (Agustin Rafael Reyes / flickr)

Among the factual stories of the original ninjas is the tale Yagyū Munetoshi (1529–1606), a renowned swordsman of the Shinkage-ryū school’s grandson, Jubei Muneyoshi, told tales of his grandfather's status as a ninja. And, Hattori Hanzō (1542–1596) was a legendary samurai warrior from the Iga province, and the  ninjutsu manuals which were subsequently published by his descendants have led many Japanese historians to define him as a “ninja master.”

The Nine Symbolic Cuts

Several ninja traditions have been preserved in popular culture, but none is so deeply-mystical and misunderstood as Ku-ji meaning “nine symbolic cuts”. Kuji (九字) means nine symbols, and Kiri (切) refers to the cutting motion. The nine symbols are named: rin, pyo, to, sha, kai, jin, retsu, zai and zen. Some experts believe this secret system of mudras was developed it China, but others insist it emanated from Vedic India. Others argue it comes from mikkyo (Japanese esoteric Buddhism), while in South Asia it is believed to be of Taoist origin, not Buddhist. Notwithstanding these differing points of view, practice of Kuji is found extensively in Shugendō, the ascetic mountain tradition of Japan, and ryobu Shinto, which is a union of Buddhist and Shinto beliefs. Therefore, it is highly likely this is the original source of the secret hand signs.

Ku-ji “nine symbolic cuts”

Ku-ji “nine symbolic cuts” (public domain)

Kuji. Science or Something Else?

It is well documented that ninjas used Kuji-Kiri to induce specific states of mind which helped them function under extreme stress. Each of the nine symbols was believed to invoke/awake the energies associated with specific abilities, for example, say a ninja had been staking out an assassination target by hiding underwater for three days. When the target finally arrived, to exit his deep meditative state, the ninja night perform the hand symbol 在/Zai: “take position.”

Stripping away the layers of supernatural notions associated with Kuji-Kiri, it is essentially a meditative process accompanied by hand signs, controlled breathing and visualization process. Together, these activities induce powerful mental states and it could also be argued that this entire process was a form of self hypnosis, which induced the reported physical changes. To get to the bottom of the thousands of reports of unexplainable ‘mind-body’ interactions, in 2012 the Mie University (School of Medicine) in Tsu City, Japan, studied the effects of Kuji-Kiri across a section of 15 “ninja professionals.”

The first part of this fascinating experiment monitored the ninjas brainwaves and heart rates before and after performing Kuji-Kiri. Each of the 15 ninjas increased their alpha-2 brainwaves, enhancing awareness and relaxation, and they all reduced beta waves which cause annoyance and anxiety. They also decreased production of theta waves which are produced in deep relaxation and sleep states. The second experiment compared the fight-or-flight response of the 15 ninjas before and after the practice of Kuji-Kiri and it monitored that all 15 ninjas “heightened their levels of alpha-2 waves and dropped their Beta waves significantly”. When these results are presented beside the brainwave patterns of deep state mediators, the results are striking.

Soft Breathing, Hard Science

Cognitive and neuroscience research has recently shed new light on the physiological effects of the meditation practice. Modern practices with ancient origins, in traditions such as Vajrayana and Hindu Tantric, have been proven to heighten sympathetic activation and phasic alertness. Additionally, traditions such as Theravada and Mahayana have been found to “illicitly heighten parasympathetic activity and tonic alertness.” What is significant in these findings is that they perfectly match, word for word, what Buddhist scripture maintains regarding “heightened arousal during Vajrayana practices" and a “calm and alert state of mind during Theravada and Mahayana types of meditation”. Here, we see a wonderful example of ancient wisdom being proved accurate with modern science.

Buddhist monk in Phu Soidao Nationalpark, Phu Soidao Nationalpark Waterfall, Thailand

Buddhist monk in Phu Soidao Nationalpark, Phu Soidao Nationalpark Waterfall, Thailand (CC by SA 3.0)

These patterns match perfectly with the results of the ninja’s brainwaves after having performed Kuji-Kiri. However, where meditation and Kuji-Kiri differ is in the speed of the altered state of consciousness. The “professional” ninja almost instantly produced the brainwaves while meditators build them up and reduce them slowly. Like Ninjutsu, Yoga teaches a series of hand gestures known as mudras which are coordinated with asanas (body poses) and pranayama (breath control). But so far as instant energy is concerned, its Kuji-Kiri every time.

Top image: Ninja warrior (public domain)

By Ashley Cowie


Adams, A. (1970). Ninja: The Invisible Assassins, p. 34

Amihai, I. and Kozhevnikov, M. (2015). The Influence of Buddhist Meditation Traditions on the Autonomic System and Attention. Biomed Res Int. Available at:

Hatsumi, M. (1988).  Essence of Ninjutsu: The Nine Traditions, p. 178

Kornicki, P. F. (1996).  Religion in Japan: Arrows to Heaven and Earth (Reprint ed.). Cambridge: Cambridge University Press. p. 2.

From Mie to the World. Mie University. Available at:

Ratti, Oscar; Westbrook, Adele (1991), Secrets of the samurai: a survey of the martial arts of feudal Japan, Tuttle Publishing, p. 325

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Ashley is a Scottish historian, author, and documentary filmmaker presenting original perspectives on historical problems in accessible and exciting ways.

He was raised in Wick, a small fishing village in the county of Caithness on the north east coast of... Read More

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