History of Ninjutsu: On Forming Hand Seals for Mental Unity

印を結ぶは精神の統一 In o musubu wa seishin no tōitsu (On Forming Hand Seals for Mental Unity) (Page 171) from the book 忍術秘錄 Ninjutsu Hiroku by 藤田西湖著 Fujita Seiko.

On Forming Hand Seals for Mental Unity

The mysterious technique of forming hand seals is considered one of the most fascinating aspects of ninjutsu (忍術, ninjutsu), but in truth, it is akin to the great invention of wireless telegraphy. It is said that by focusing one’s mind, a person can, through mental action alone, freely manipulate an opponent.

The art of forming hand seals is, in essence, a method to unify one’s spirit and build the conviction of inevitable victory. Even in the most desperate situations, when all seems lost, it hones the resolve to remain unshaken, to calm others in the midst of flashing swords, to sharpen the mind’s eye, and to devise a way to carve a path forward.

There is no one stronger than a person who does not fear death. The secret of martial arts lies in finding a way out, maintaining a cool gaze within the enemy’s encirclement, and opening a path to survival. It is said that Shukaku (孔明, Shukaku), seeing Yūshi (遊子, Yūshi) at the bridge gate, played the koto to skillfully repel the cunning Chūtai (仲題, Chūtai).

This is the same profound truth: forming hand seals is akin to playing the koto, a matter of the heart. Only when this unshaken focus is achieved can the marvelous techniques of ninjutsu succeed.

As a method of mental unification, ancient ninja traditions dictate that the ninja first chant a mantra and form hand seals. Through this, the practitioner gains mental stability, ties their spirit to faith, and strengthens their confidence.

Since ancient times, 真言宗 Shingon-shū has taught the integration of the three secrets: body, speech, and mind. In Shingon doctrine, it is said that when these three are perfectly aligned, one can achieve instant enlightenment. In the way of the ninja, the body is linked to hand seals, speech to mantras, and mind to contemplation.

When seals, mantras, and contemplation align, it is said that divine power is immediately manifested. Thus, even ninjutsu, systematically developed, relies on divine and Buddhist principles. Seeking divine protection by aligning oneself rightly was undoubtedly the sole spiritual pillar for ninja who ventured into perilous situations.

The Nine-Character Protection Method

Since ancient times, there has been a method called the 九字護身法 Kuji Goshinhō, regarded as a crucial principle of the nine characters in military strategy.

“It is said: The matter of the nine characters is a great method for protecting the mind and is not a trivial thing. To practice this method, one must first, every morning, wash hands and rinse the mouth, face north to expel impure breath, turn east to clear the mouth, draw breath inward, and inhale life three times. Then, strike the teeth thirty-six times, calm the mind, and practice this method.

Whether traveling, in the mountains, fields, during night journeys, in confined rooms, or in solitude, if one performs this diligently, their own power will instantly increase, and all enemies, demons, foxes, and beasts will be unable to seize opportunities or cause obstructions.

Believe in this mysterious and unfathomable secret method without doubt, and practice it with utmost sincerity. However, as this is a sacred method, if the practitioner lacks the virtues of benevolence, compassion, loyalty, and filial piety, or indulges in unlawful and unjust acts, it will yield no results and may even bring calamity. If one’s heart is honest, pure, and upright, fears the way of heaven, does not betray the way of humanity, values their family duties, and practices this method sincerely, they will surely gain benefits, avoid all disasters such as thieves, water, fire, and other troubles, and find peace and protection. This method is meant to guide laypeople and reflects the teachings of a master.

The great principle of the nine characters in military strategy, bestowed by Ōmarimon-ten (大摩利文算天, Ōmarimon-ten), strengthens body and mind, enhances power, repels enemies, subdues demons, destroys evil spirits, malevolent ghosts, and monsters, removes all dangers and difficulties, and fulfills all desires to perfection. Those who practice it devoutly and for a long time will surely experience its efficacy.”

It is written that Buddhas and gods protect and aid virtuous men and women, but those who live for selfish desires with impure hearts will not receive this merit. This truth is the essence of the samurai spirit and martial arts.

Regarding the formation of these seals, there are nine distinct methods, inspired by the Kuji (nine characters). These are: Dokko-in (独鈷印, Dokko-in), Dai-kongōrin-in (大金剛輪印, Dai-kongōrin-in), Gai-shishi-in (外獅子印, Gai-shishi-in), Nai-shishi-in (内獅子印, Nai-shishi-in), Gai-baku-in (外縛印, Gai-baku-in), Nai-baku-in (内縛印, Nai-baku-in), Chiken-in (智拳印, Chiken-in), Nichirin-in (日輪印, Nichirin-in), and Ongyō-in (隠形印, Ongyō-in).

Finally, there is the universal seal for cutting the nine-character seals. These correspond to the well-known nine characters: “Rin pyō tō sha kai jin retsu zai zen”. They are illustrated as follows:

Rin: Dokko-in (独鈷印, Dokko-in), Turbid Air Seal
The right hand is clasped inward, with the index fingers raised and joined.
Amaterasu Ōmikami (天照皇大神, Amaterasu Ōmikami), Bishamon-ten (毘沙門天, Bishamon-ten)

Pyō: Dai-kongōrin-in (大金剛輪印, Dai-kongōrin-in), Great Diamond Wheel Seal
Both hands are clasped inward, index fingers lowered, entwined with the middle fingers.
Shō Hachiman Daijin (正八幡大神, Shō Hachiman Daijin), Jūichimen Kannon (十一面観世音, Jūichimen Kannon)

Tō: Gai-shishi-in (外獅子印, Gai-shishi-in), Outer Lion Seal
The left and right middle fingers entwine the index fingers, with thumbs, ring fingers, and pinkies raised and joined.
Kasuga Daimyōjin (春日大明神, Kasuga Daimyōjin), Nyoirin Kannon (如意輪観世音, Nyoirin Kannon)

Sha: Nai-shishi-in (内獅子印, Nai-shishi-in), Inner Lion Seal
The left and right middle fingers entwine the ring fingers, with thumbs, index fingers, and pinkies raised and joined.
Kamo Myōjin (加茂明神, Kamo Myōjin), Fudō Myōō (不動明王, Fudō Myōō)

Kai: Gai-baku-in (外縛印, Gai-baku-in), Outer Binding Seal
Both hands are clasped outward.
Inari Daimyōjin (稲荷大明神, Inari Daimyōjin), Aizen Myōō (愛染明王, Aizen Myōō)

Jin: Nai-baku-in (内縛印, Nai-baku-in), Inner Binding Seal
All ten fingers are clasped inward.
Sumiyoshi Daimyōjin (住吉大明神, Sumiyoshi Daimyōjin), Shō Kannon (正観世音, Shō Kannon)

Retsu: Chiken-in (智拳印, Chiken-in), Wisdom Fist Seal
The left hand’s four fingers are clasped, index finger raised, and the right hand grasps the left index finger as such.
Niu Daimyōjin (丹生大明神, Niu Daimyōjin), Amida Nyorai (阿弥陀如来, Amida Nyorai)

Zai: Nichirin-in (日輪印, Nichirin-in), Sun Wheel Seal
The thumbs and index fingers of both hands touch at the tips, with the other four fingers spread apart.
Nitten-shi (日天子, Nitten-shi), Jigoku Bosatsu (躋勒菩薩, Jigoku Bosatsu)

Zen: Ongyō-in (隠形印, Ongyō-in), Hidden Form Seal
The left hand is clenched hollowly and placed over the right hand.
Marishi-ten (摩利支天, Marishi-ten), Monju Bosatsu (文殊菩薩, Monju Bosatsu)

With a sword seal formed, one chants the nine characters while moving as described.

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