Ninja Kuji-In Mudra from Vairocanasambodhi Sutra?

[Rakshasa]

So I was browsing through the Vairocanasambodhi Sutra (Mahavairocana Sutra) which is one of the main texts of esoteric Buddhist sects like Shingon and came upon chapter 14 "Eight Secret Seals". And to my surprise it explains eight Mudras of Buddhist practice which appear to be quite the same as the Kuji-In Mudras used by the ancient Ninjas for enhancing their martial and psychic power.

You can read the Sutra here
https://www.bdkamerica.org/digital/dBET ... a_2005.pdf

I have read a lot of articles about Ninja and usually the opinion of scholars, academicians and Ninja practitioners is that these Mudra practice originated from Taoist or Shinto or Shamanic elements from either Japan or China, but it seems to be directly taken from Buddhist sutra. Could it be that the Ninjas were influenced by Shingon Buddhists? I think it is very plausible that Ninjas took advice from Shingon monks in the military arts.

[Rakshasa]

Thereupon the World-honored One Vairocana again gazed upon the entire
great assembly and addressed the vajradhara Lord of Mysteries, saying, “Son
of the Buddha, there are eight secret seals which are most secret. [When used
in] the stations of the holy divinities [in the maṇḍala], their awesome divinity
is the same [as that of the deities]; they are characterized by their own
mantra path (i.e., mantras) and have [their own] maṇḍalas, and one should
intercorrespond with them as with one’s own deity. If they rely on [this] ritual
teaching, bodhisattvas cultivating bodhisattva practices via the gateway
of mantras should know that they themselves will dwell in the form of their
own deity, firm and unmoving, and after having known [the state of] their
own deity, they will abide in the manner of their own deity and obtain siddhi.
“What are the eight seals? With the right and left hands form the hollow
hand-clasp and spread the little fingers and forefingers apart as if to radiate
blazing light. This is the seal ‘birth of the World-honored One’s great
majesty.’ Its maṇḍala is triangular and has rays of light. The mantra is: Namaḥ
samantabuddhānāṃ, raṃ raḥ svāhā. (Homage to all Buddhas! Raṃ raḥ!
svāhā!) [248]
“Then with this [same] seal, bend the forefingers [down] on top of the
thumbs like the shape of the [Sanskrit] letter Va. This is the seal ‘adamantine
indestructibility of the World-honored One.’ Its maṇḍala is like the letter
Va in appearance (i.e., round) and has adamantine light. The mantra is:
Namaḥ samanta buddhā nāṃ, vaṃ vaḥ svāhā. (Homage to all Buddhas! Vaṃ
vaḥ! svāhā!) [249]
“Then, with the first seal, spread the ring fingers and middle fingers
apart. This is called ‘lotus-flower matrix seal.’ Its maṇḍala is like a lunar
disc in appearance and is surrounded by padma flowers. The mantra is:
Namaḥ samantabuddhānāṃ, saṃ saḥ svāhā. (Homage to all Buddhas

This is the excerpt from the chapter. Do Shingon monks still practice the Eight secret seals apart from the Ninjas?

[Doko]

I'm not sure if the Kuji-In is used in Shingon but we were recently watching a Shugendo documentary (Shugendo Now) and saw this being used.

[Rakshasa]

I'm not sure if the Kuji-In is used in Shingon but we were recently watching a Shugendo documentary (Shugendo Now) and saw this being used.

I think Mahavairocana Sutra is the central text of the Shingon sect, right? I have the whole pdf which I downloaded from the internet (it is freely available). I was randomly browsing through the text and stumbled upon the eight secret seals. Since I am martial arts enthusiast and know that there exists a practice in the Ninjutsu style in which Ninjas make hand seals (mudras) to attain certain abilities, I was curious to see if Kuji In of Ninjas is the same as it is described in Mahavairocana Sutra. And it seems it is indeed the same. This is interesting because it basically means that the Ninjas as a warrior sect arose from the influence of Shingon Buddhism (the Shingon priests probably tried helping farmers and peasants to fight oppression?). Similar was the situation in China where Shaolin monks started developing Kung Fu, although I dont know how much Buddhism was used in its creation.

EDIT Okay I just came to know that Shugendo is another esoteric sect from Japan so the Ninjas must have been influenced by it instead of Shingon. In any case, it is pretty clear that the origin of these Seals is from Mahavairocana Sutra. I wonder why so many historians and scholars about Ninjas still claim that the practice originated among the Taoists or Shintoists. I've seen many practitioners of Ninjutsu claim the same, which is surprising since the proof is in the pudding.

[Doko]

There are several schools in Japan that could be considered ninjutsu. The different schools have their own unique history. Kukisinden ryu may be of interest to you. Togakure Ryu has a connection to Tendai-shu. They say that the founder of Togakure Ryu was trained by So-O who is also credited with starting the Kaihogyo.

[WuMing]

I'm not sure if the Kuji-In is used in Shingon ....

I think Mahavairocana Sutra is the central text of the Shingon sect, right? ... that the Ninjas as a warrior sect arose from the influence of Shingon Buddhism ...

... that Shugendo is another esoteric sect from Japan so the Ninjas must have been influenced by it instead of Shingon.....

Yes, the Mahavairocana Sutra is one of the most important text in Shingon. AFAIK, there is no relationship between Ninjutsu and Shingon, they have nothing in common really, it's all made-up.

[eijo]

In any case, it is pretty clear that the origin of these Seals is from Mahavairocana Sutra.

The "eight secret seals" from the MV are a basic part of the curriculum of Shingon Buddhism. They are completely unalike in appearance from the Shugendo practice you mention, and of course the MV mudras are for the eight deities in the center of the mandala, and are accompanied with Sanskrit mantras where the Shugendo practice uses only single Chinese characters. The two sets of seals are completely unrelated.