Many years ago (about 15~) in my days of obsessively playing the Tenchu series of video games, I was exploring every nick-and-cranny of all the levels, and in one of the levels that took place in the mountain-top Buddhist monastery, I noticed a small detail where there was this sort of chopping blade sticking out of a block of wood just like a hatchet might.
A few years later I became quite interested in this short battle royal type of anime and manga called Basilisk: Kouga Ninpou Cho (and later the novel that it came from). In it I was drawn to a character named Yashamaru from the Iga clan, and besides his distinct long-distance fighting style, he also carried as similar short cleaver, though between the three forms of media he never uses it, in the anime adaptation he does draw it so that you can see the angle and length (screen shots provided in the slideshow below.
Finally, in around 2008, when I started to take studying Japanese and the ninja more seriously, I acquired a copy of the Shinobi Hiden (or Ninpiden), and before even having a translated copy, I knew what the illustration I was looking at was.
I have seen two different ways to write Nata: the first seems to be the most common way 鉈, and seemingly less common way, 屶.
The first, the dictionary tends to translate as “hatchet”, but that is an evident transliteration to English based on it’s general use. However, when we break the radicals apart we find “stretch” (它) and “metal” (金). In my mind, this gives the image of a simple elongated piece of metal; which could stretch back in history as a tool quite some ways.
The second way, I cannot recall where I got the kanji from initially, but a quick google search shows the very same tool. One doesn’t need a dictionary to see that this kanji easily breaks down to “mountain” (山) and “blade” or “sword” (刀), so some form of mountain blade (see the Tenchu reference above). However, the Japanese dictionaries that I have don’t have this character. Instead, Wiktionary shows that 屶, is a variant form of 會. So in looking at that…
The relevant seal inscription form (see image to the right) is a variant form (through phonosemantics) of 介 “reduce” and 曾 “pile” or “mass” (That’s a bit of an adventure on how it gets there, but current dictionary’s go in a different direction as usual). Thus this character can refer to reducing a pile of something.
Interestingly, 會, which has come to refer to “reducing the space between things”, and as such nowadays means something like “gathering”, “to meet”, etc., and is usually simplified to “awasu” or “awaseru” (会).
Nata in the Shinobi Hiden
In the Shinobi Hiden, it is listed as a “Tetsu” or “Kurogane” (鉄), which basically means “Iron”. I’m not yet sure if the name changed at some point, but the common term for it is currently a “Nata” (鉈), referring to something like a hatchet.
In the Shinobi Hiden, it primarily details the proportions and materials used for it and it’s scabbard. It is even detailed at the end that a hole should be in the end of the scabbard and a “thieves gimbal lantern” can be attached.
What can be inferred
A point of interest is that it details to “Be sure the iron blade is well forged. Do this in case it is used in place of a sword, and thus the blade is of the most importance.” (Cummins, 2011). Though there is a growing opinion that the ninja would not have their own martial art, one can note that a machete or hatchet handles very differently from a sword or spear. As a result, in order to treat this tool as a sword, the biomechanics of ones martial tradition would have to allow for more than a familiarity with swords, spear, halberds, etc. but also a unity of combative methodology between any weapon.
This is precisely what we see in traditions such as Gyokko-ryu, Koto-ryu, Togakure-ryu, and similar traditions that have some part of their history in the Iga region of Japan.
It is important to remember that though such a tool can be weaponized, it is not in itself a weapon and is to this day used by foresters and gardeners alike. Used like both that of a hatchet and a machete. I have herd several accounts now of North American outdoors-men (and women) now preferring the Nata over that of their choppers or hatchets for their every day use.
How the Nata ended up being associated with the ninja in a few video games and anime is honestly beyond me, but for those guys dressed up in black masks and running through the bush with their Filipino machetes, this would be the direction that they would want to go.
The Ninpiden – True Ninja Traditions: And the Unknown Ninja Scroll
Etymological Dictionary of Han/Chinese Characters. By Lawrence J. Howell, Research Collaborator Hikaru Morimoto
In the Bujinkan organization’s vast collection of teachings, techniques, and tools, there are a wide assortment of unusual weapons and tools that have been adopted, adapted, and re-purposed to fit new needs and intentions. This isn’t new for the martial arts, a tertiary glance at Okinawan martial arts will illustrate that. However, one of the more exotic and supposedly specialized tools has a great wealth of mystery and misconceptions – the shukō.
This is a highly misunderstood tool that has had much of it’s qualities exaggerated, and even it’s place in history re-shaped to fit many people’s conceptions and ideals of farmer-warriors and the ninja. Some of the things that are misunderstood:
The shukō are unique to ninjutsu,
The name means “tiger hands” (手虎),
The shukō were designed for climbing trees,
and so on…
In regards to these things, they aren’t always easy to source, but they do tend to have a certain logic about them so I’ll peel them off quickly: The notion that the shukō are unique to the ninja don’t generally make much sense as anything visibly unique to the ninja would simply give up one’s cover; as such, like many such interesting tools, they originate in agricultural practices (elaborated on later).
The name means “hand hooks” (手鉤) not “tiger hands” (手虎), though a viable homonym, there are literally no reputable sources for this way of writing the name. One may take some artistic license in regards to such things, and the connection is an easy one to make, but neither the history of the tool, nor any prevalent sources support this. One source that we can look to is in Takamatsu Toshitsugu‘s own writing, one of the densho of the Togakure-ryū (see the above slideshow), where by his hand, it is written 手鉤. This kanji is also reproduced in Masaaki Hatsumi‘s “Way of the Ninja” (page 48).
The foundation and evolution of the shukō begins in the agricultural fields of ancient Japan around the Kofun period (c. 250 CE – 538 CE), when the establishment of iron tools really started to take hold in rural Japan. At this time, the source tools we can find is that of the Asakagi (fiber hook; 麻鉤), also called the tekagi (with the same spelling as shukō; 手鉤), used for hooking bails of straw, hay, wheat, and in early times, bundles of rice, for manual moving and transportation.
There was also the Asanō (shallow agriculture; 浅農), a three-to-five pronged claw on a shaft, used for hand plowing gardens and smaller crops. This could also be used for the same purpose as the above mentioned asakagi in moving bails of various horticulture product.
Quite a while later, during the Heian period (794 – 1185 CE), there was a certain merger to this tool in certain regions of Japan. At this point, the development of the tekkō kagi (claws that cover the hand; 手甲鉤) can be seen (source waiting for release ). This was used similar to that of a pitch-fork, a tool used for scooping up hay, straw, and wheat manually.
Sometime in the Sengoku period (1467 – c. 1603) certain regions developed a variation of the tekkō kagi, but with the hooks worn on the inside of the palms, often with cloth or leather sleeves similar in use to chaps in order to protect the bare skin from whatever produce was being handled (see figure 3). This allowed better leverage and handling when lifting and moving bails (koku; 石) of rice by hand. The version made popular by Togakure-ryūninjutsu is made of a metal band that wraps the palm, and a wrist band. The hooks are located on the inside of the palm (see figure 2).
Within the martial arts of Togakure-ryū ninjutsu, there are three particular ways to go about it:
Applying this to augment one’s unarmed fighting (taijutsu; 体術),
Usage for fleeing techniques (Taijutsu Ukemi Gata; 体術受身型),
Kata that are specifically made to utilize shukō (Santō Tonkō Gata; 鼠逃遁甲型)
The first approach, and most common one it seems, is to explore one’s taijutsu while wearing shukō. This, however, requires that you understand the qualities of the tool. For example, one can assume that you could simply slap the enemy with the claws and have some exciting results. However, what then happens when the claws get stuck in bone? Now this slows you down; this is also where one can quickly see where this was a tool before it was a weapon – the hooks are designed for fibrous produce, not human… consumption.
Instead, one uses the weight of the metal band and the shape of it in various ways, while moving in an exceptionally light way, including changing how one delivers strikes. the forms of boshiken (thumb fist; 拇指拳), shutō (edge of hand; 手刀), and even fudoken (clenched fist; 不動拳) are forced to change to accommodate the shape of the shukō. As such the following gokui is relevant:
“Sutemi also contains a sense of moving as though empty handed, even while holding a tool.”
– Masaaki Hatsumi
The second way draws from the more acrobatic section of Togakure-ryū, from the Togakure-ryū ninjutsu hidensho (戸隠流忍術秘傳書), which is shown in Figure 1 above. This details some vague forms of evading sword attacks and takes into account matters such as striking the opponents vitals with the metal band of the shukō as well as using it to catch a sword blade in the hands and hoist the weapon away from the enemy.
The Escape Forms
Finally, there is the Santō Tonkō gata (鼠逃遁甲型) found in the Shinjin Ichinyo no maki (神人一如之巻). This writing lays out the primary techniques of the shukō, shuriken (throwing blades; 手裏剣), and metsubushi (blinding powder; 目潰し). These forms are derived from Hajutsu (破術), and deal with dire situations where one is detected and forced into combat. This is different from conventional kata dealing with the defeat of the enemy in that these kata detail how to escape from various grabs, stun or weaken the enemy and flee or hide.
the second section deals with being unarmed (or with shukō and various other tools) while facing an armed assailant. These techniques again don’t necessarily deal with killing the enemy, but stunning or disabling, and then fleeing or hiding.
The third section is regarding situations where you are discovered, cornered, and outnumbered. Then things like stones, metsubushi, and misdirection is deployed in order to survive and escape.
As can be seen above, although certain groups have weaponized this uncommon farm implement, it is not inherently a weapon. Shukō are not weapons for war, they are soto no mono (improvised weapons; 外の物), but before being a weapon, it was a tool for carrying things on the back. So a warrior or samurai who is working in the fields is suddenly attacked by somebody and he used the tools by accident. That is to say the shukō wasn’t something you necessarily carried (though see the photos at the end of this article to see how they were carried), unless that was a planned thing.
And the techniques involved further exemplify this, as well as a very important gokui of Togakure-ryū:
“Win without drawing; if you must draw, don’t cut. Just forebear. Know that it is a grave thing to take a life.“
 It has been stated in other sources across the Internet, but here is an example where a notable amount of misinformation has been cast. I don’t know where this information comes from, but according the “About” page, it is linked to To-shin-do. I emphasize that this is not a slight against Stephen Hayes at all, but the information has been clearly inaccurate.
 Even in North America, though notably later (circa 16th century), I personally can attest to seeing tools similar to the Tekkō kagi for the purpose of moving handfuls of hay and straw before the bundling of hay bails with large scooping movements, having grown up on a horse farm in an French Acadian family (the initial European settlers of the country to be known as Canada).
 I have translated several primary sources on commission, and this is one such one that is under a confidentiality clause; it is regarding agricultural tools and their usage during the Kamakura (1185–1333) or Muromachi (1336–1573) periods. I can say that this is a long gap in history, and there was tremendous developments and improvements in metallurgy during this time as there has always been two major influences in historical development: military, and entertainment – in this case the Sengoku jidai (warring states period) stretched from 1467 to 1603; a very long time, but a very scientifically influential time.
 “Smooth is slow; slow is hidden.” (滑らかさは遅いです、遅いが隠されている。)
 This particular scroll teaches not only the fighting techniques of the tradition, but also the philosophical principles of “harmonizing with nature”, that is to say, Shinjin Ichinyo. As I have explained elsewhere, the notion of the kami (神) in the Shinto faith, are like the manifestations of the elements of nature; and like that, this scroll teaches how to escape and hide with the five phases (gogyo; 五行) as inspiration. As such, learning to rely on and harmonize (become one with) the phases of nature is becoming one with the kami.
 “Hajutsu no hō is a very violent method of combat, which requires a deep understanding of the human anatomy as well as the ability to move with fluidity. Hajutsu no hō allows the practitioner, among other things, to incorporate the use of the various types of weapons. It encompasses the likes of kosshi-jutsu and koppō jutsu, the art of kyūsho (急所) and kyūsho (求所 or 救所). Here, the two words have the same sound, but the characters are different. They are complementary sciences, which shows why kosshi-jutsu and koppō-justsu were always transmitted together.” (Zoughari pp 77)