Ko-Hoki KatanaKo-Hoki

periodHeian (ca. 987 - 1050 AD)
designationNBTHK Juyo Token
nakagoo-suriage mumei
nagasa68.2 cm
sori1.5 cm
motohaba2.6 cm
sakihaba1.6 cm
kissaki2.6 cm
nakago nagasa17.6 cm
nakago sori0.1 cm

Old books put Hoki province in the middle of the earliest traditions of iron manufacture. Hoki had good quality iron sand which could be used to produce iron and steel. Hoki was on the sea, backed with highlands and faced directly toward China and Korea where there were native technologies already developed for crafting edged weapons. These were a natural market for the high quality iron and steel raw materials produced in Hoki. In theory then there develops an interchange between Hoki and the mainland with raw material going one way, and finished products (swords), and eventually craftsmen and their technology coming over and imported into Japan. This interchange becomes the seed for all Japanese sword making traditions.

This interchange takes place during the during the Kofun through Nara periods (approx. 200 AD to 700 AD) and many of these imported weapons and mainland influenced styles have examples stored at the Shoso-in by the order of Emperor Shomu and Empress Komyo 1,300 years ago. The period before the shinogi-zukuri tachi we call the Jokoto period (ancient sword period) in sword study, and the swords themselves which are not tachi we call chokuto. Many of these swords remain stored today and are the origin or at least inspiration for the sword manufacturing traditions that would become specialized and highly developed throughout Japanese history. These old swords have many interesting shapes, some of which are only vaguely related to what we consider to be Japanese swords now, due to their origin on the Asian mainland in style if not in actual manufacture. Most of these swords are straight and simplistic compared to the refined elegance of later Japanese work, and reflect styles of fighting involving thrusting or at best simple hacking.


National Treasure Dojigiri Yasutsuna

It was during the time of Yasutsuna that the changeover from the straight edge blade introduced from the mainland was taking form into a sword with a sori, which we know today as Shinogi Tsukuri and probably Yasutsuna may have made some contribution to this change. Popularly this credit is given to the legendary [i.e. did not likely exist] Amakuni of Yamato province. Albert Yamanaka, Nihonto Newsletters

It was traditionally thought that Yasutsuna appeared around 800AD and began forging swords in Hoki. It's at this juncture that he and his students (collectively known as the Ko-Hoki school) are part of the revolution where the chokuto are replaced by a ridged, curved long sword which we know as the shinogi-zukuri tachi. His most famous work is the Dojigiri Yasutsuna (the Demon-Cutter) which today is one of the five most famous swords in Japan and has a long legend from which it gets its name. These five swords are the Tenka Go Ken, or the Five Swords under Heaven and along with the Dojigiri they are the Oni-maru Kunitsuna (named for killing a ghost), the O-Denta Mitsuyo (named for its magnificent presence), the Mikazuki Munechika (named for the crescent moon shapes in the hamon) and the Juzu-maru Tsunetsugu, an Aoe blade named for its Buddhist priest owner. These blades are all Kokuho (National Treasures of Japan) or Juyo Bunkazai (Important Cultural Artifacts) and are in the category of artifacts that are illegal to export from Japan.

Yasutsuna's Dojigiri is Kokuho today and was handed down from many daimyo through Oda Nobunaga, then to Toyotomi Hideyoshi, and on to Tokugawa Ieyasu (the three great warlords responsible for uniting Japan). This sword was one of the first meibutsu and registered in the Kyoho Meibutsu Cho as one of the great works existing in the Edo period. Today it resides the Tokyo National Museum.

Today the work of Yasutsuna and his group is placed as being just ahead of the earliest emergence of the Ko-Bizen smiths: around the Eien period (987 AD). This likely still makes them the originating group for the evolution of the chokuto to tachi shape, though this honor is also given to Sanjo Munechika in Yamashiro province. When it goes back this far it's very difficult to determine facts and it becomes a matter of further research and debate. What we do know is that Ko-Hoki is probably the first or second major group of smiths making swords in the modern style we're familiar with, which breaks from the odd experimental shapes of swords that came from the Chinese mainland or were forged locally and stored in the Shoso-in repository.

The work of the Ko-Hoki smiths has a particularly unrestrained and free feeling to it, that incorporates a tone of wildness and lacks the controlled refinement seen in earliest Yamashiro and Bizen works. We could possibly make the comparison of Miyamoto Musashi who had a reputation of avoiding baths and decorating himself appropriately encountering a very formal and cultured samurai on the road in a forest. They are two different aspects of the same ideal but coming at it from very different directions and principles.

sword picture

While Ko-Hoki work is considered rustic contrary to the refined Ko-Yamashiro and Ko-Bizen work, it also reached heights of flamboyance that these other two schools did not approach as they remained rather tightly within certain limits of expression. Ko-Hoki's deki covered the steel with ji nie and filled the hamon with nie, while the forging showed a great degree of contrast in color and texture.


The Kokuho Shiro-Izumi Masamune in Ko-Hoki style

Any casual reading about the great master Soshu Masamune will usually be prefixed with the statement that he was inspired by Ko-Hoki and Ko-Bizen works and highly influenced by them.

It should be noted however that [Soshu] Masamune's forte was producing midareba consisting of notare which was as it were, his innovation. He also produced works which, either partly or wholly, had either Ko-Bizen or Ko-Hoki characteristics. One example of his Ko-Bizen style work is named Tarosaku and the other type [an example of Ho-Hoki style work] is named Shiro-Izumi. The key factor in Masamune's works that makes them different from Ko-Bizen and Hoki works is the pronounced dominance of nie forming kinsuji and chikei. Dr. Honma Junji

The same is written about Norishige, and Norishige even more so than Masamune was able to make contemporary works in Ko-Hoki style. When these great masters were working in the early 1300s, Ko-Hoki works of three centuries prior would be the antiques of their day, holdovers from an earlier time with techniques and mysteries they wished to unlock. These two together with Go Yoshihiro represent the very peak of the Soshu mountain and influence of Ko-Hoki is one of the primary factors in why their style became as exciting as it did.

... [a reference Norishige] once belonged to the late Count Ito Miyoji. A well established Meiji-Taisho time connoisseur Takenaka is known to have appraised it to be Hoki Yasutsuna instead of Norishige. Research work continued and today no one that sees the blade firsthand would ever insist it had to be Yasutsuna. I can repeatedly say, like Masamune, Norishige too tried to reproduce both Ko-Bizen and Ho-Hoki workmanship. Dr. Honma Junji

Ko-Hoki steel is usually described as blackish and dark which is something shared in particular with Go and Norishige, while the nie become very bright and shining. Activities are prominent in ji and ha and these will not always follow an imposed structure. Some of the earliest Yamashiro works can be like this though the hamon structure will still stay within bounds of ko-midare. With Ko-Hoki you don't necessary know what you will get, and probably the smiths were not exactly certain either. This freedom and lack of expectations seems to be what allowed them to produce some unusual and breathtaking works which in turn became the inspirations behind the greatest smiths of all time, who in their own turn would cast long shadows for many centuries with each newly born master eventually trying his own hand at emulating the style of the Soshu smiths at one point or another.

The primary source for iron in Hoki was the Hino river which runs through the mountains in Chugoku and eventually empties into the sea. Running through these mineral rich highlands it deposits high quality iron sand along its banks, where the smiths of Hoki province gathered it to use for forging steel. Different spots along the river deposited different types of iron sand. Shin-satetsu containing magnetite would be concentrated on the west bank and Akamezuna containing hematite on the east bank. This access to naturally sorted raw materials is something that flavored Hoki workmanship as we see incredible varieties of nie and different colors in the jihada as they likely used different grades of steel based on these raw materials before forging them together into their final product.

Hoki steel was even highlighted in 1930s era advertisements for Gassan Sadakatsu blades, being the diamond hard steel used to form the positive steel in the construction of his blades. This was balanced out by a negative steel and a blade steel. We can see in his ayasugi hada swords the different color standing out quite clearly when he laminated layers of these different steels into a final product.

The presence of a great amount of ji-nie is a distinct characteristic of this [Ko-Hoki] school. Also, the great many chikei almost suggesting Norishige's work is another characteristic of this school. NBTHK Journal

This variety of material is what gives great contrast in color and appearance and seems to be what Norishige in particular pursued in producing his trademark matsukawa hada. These works of Norishige and Ko-Hoki can be so similar that they are often confused in kantei. When the results come together perfectly when working these different grades of steel, great amounts of nie and chikei are produced along with fantastic hataraki in the ji and hamon. So by inspecting one of these influential works it is self evident what Masamune and Norishige saw and became inspired by, the same way we look at works of the Soshu masters and become quite inspired ourselves.

sword picture

Norishige forges so-called matsukawa hada then tempers notare mixed with gunome in thick nie-deki then a lot of kinsuji and sunagashi are seen inside the hamon. Also, he demonstrates a workmanship that was modelled on the forging style of Ko-Bizen and Ko-Hoki smiths. Therefore it is understandable that many votes went [incorrectly during kantei] to Ko-Hoki and Ko-Bizen smiths between the end of the Heian and beginning of Kamakura periods. NBTHK Journal

Forging swords out of different grades of steel made for incredible activities and particular beauty as we see in the work of Norishige, but it was also subject to flaws when the layers failed to laminate. We see these kinds of production issues in Ko-Hoki works, in Norishige, in the Uda smiths who follow Norishige. We see them again in Shinto smiths who tried to copy Norishige. Hankei in particular, a great master of the early Shinto period did his best to emulate Norishige but felt short. But in one area he faithfully reproduced the forging flaws we often see in Norishige to an even larger quantity and it must have driven him quite mad at trying to make his material work. In spite of these issues, the results show charm and beauty which resonates and all of the above have achieved at Tokubetsu Juyo levels.

The Ko-Hoki smiths seemed to have shared a family name of Ohara based on the village they worked in and Ohara Sanemori in particular signed with this name. Otherwise the rest of them signed in two characters and we know today of various smith names: Sadatsuna, Sanemori, Moritsuna, Aritsuna, Sanekage, Kunimune, Sukenaga, Ieyasu, and Yasuie all part of the extended family and compose roughly four generations of smiths in Ko-Hoki. Some of their work is completely gone now considering the age involved. Trying to work the lineage is involves some guesswork and different books put them in different orders. Some of these are so rare they have almost been lost to history. For instance the NBTHK has only encountered one blade by Sukenaga and it is ranked Tokubetsu Juyo.

sword picture

Of these the workmanship overlaps and can be hard to tell apart, especially due to the fact that they are rather unrestrained in their approach to sword crafting. Yasuie has left a work which is also Kokuho (there are only 110 swords that are Kokuho in total), and there are a combined eight Juyo Bunkazai amongst the Ko-Hoki smiths. The NBTHK has authorized 71 Ko-Hoki items at the Juyo level or higher. Of those 71, eight are Tokubetsu Juyo. Works that are not signed are usually just designated as Ko-Hoki, meaning one of the above named smiths made them but it's not clear which one due to the overlapping work styles. Timing them is also difficult as traditionally they begin around 800 and the last swordsmiths are working around Tentoku which is 957AD, and so the Ko-Hoki group by this measure are extinguished well before Ko-Bizen comes to prominence. It is more likely that Yasutsuna comes a bit before Ko-Bizen and is the primary influence behind Ko-Bizen as Fujishiro points out. Bizen with its ever advancing technology and Yamashiro, resident in the middle of Kyoto with immediate access to noble customers, then go on to out-compete the Hoki smiths and essentially undermine their economic viability which had been previously based on access to superior resources. Distance from market, and the advanced techniques of Bizen see the Ko-Hoki smiths vanish before the Heian period is over.

Ohara Sanemori had a peculiar habit of signing using the character katsu ()above his name from time to time. This can also be read as sho. This is another thing that Norishige would use 300 years later that ties the smiths together.

We know that the Etchū-smith Norishige (則重) tried to reproduce the old Ko-Hōki style and several extant blades definitely show his approach. And there exists a tokubetsu-jūyō tantō of Norishige which also bears the character Shō/Kachi. Like on the Sanemori blade [pictured], the character in question is chiselled above the mekugi-ana, that means not directly connected to the name of the smith. So maybe this character was a way for Norishige to show that he knows Sanemori's blades very well. Anyway, the reproduction of the Ko-Hōki style by Norishige and this single character known to be used by Sanemori is in my opinion too much to be just a coincidence. Markus Sesko (Blog)

Fujishiro places Yasutsuna at Eien in the Heian period, so around 987 AD and says that the time period is not that far away from Ko-Bizen in accordance with my statement above. He further states that in his opinion sword technology flowed from Hoki to Bizen. This would make Yasutsuna's Hoki group of smiths a major influence over Bizen, Soshu and Mino too since it is an offshoot of Soshu.

Judging from [this Soshu Sadamune] hamon's hataraki, it appears that the Soshu Den style was influenced by Ko-Hoki work. This shows a lot of dynamic nie hataraki but it is not an artificial look, and it shows Sadamune's well controlled artistic sense, and is one of his best blades. NBTHK Journal

This is three of the five major traditions of sword making that owe a lot to what went on in Hoki province under Yasutsuna. The Hoki smiths Yasutsuna (Sai-jo saku) Hoki smiths Sanemori (Sai-jo saku), Moritsuna (Jo-jo saku) and Aritsuna (Jo-jo saku) retain high ratings while Fujishiro didn't rate the others, not because of lack of skill but because he never saw them due to the rarity of the work. It is safe to understand them at Sai-jo and Jo-jo levels, especially as at their time they were doing pioneering and unprecedented work. Some of these smiths Fujishiro did not even see, like Moritsuna, but assigned a skill level based on handed down reputation.

There are other works still lurking in the shadows and not published at Juyo yet, but this collection of swords is very small and not likely to grow very large at this point in time, after 60 Juyo sessions. In total the amount of work left to us from Ko-Hoki is very rare, and given its extreme age of around 1,000 years, is very precious. Especially given its role as one of the primary inspirations for Masamune and Norishige, these Ko-Hoki works are of interest in being able to understand the origins of Soshu and what makes it special.

Juyo Token Ko-Hoki Katana

Juyo Token Ko-Hoki Katana

This is a wonderful sword from the Heian period attributed to the Ko-Hoki school. The condition is no longer perfect, in particular there is a rough patch about midway through it on one side, but the activities of nie are outstanding everywhere in this sword. It is a masterpiece that shows a lot to be appreciated. The jihada is quite like Norishige as would be expected though Norishige forged at a more refined level as we know. The hamon at first glance in presentation and form looks just like Soshu den. However the blade with ko-kissaki and gentle sugata immediately hits home as a Heian period work. The NBTHK points out that the blade shows a lot of similarities to Ko-Bizen, but the hamon lacks the structure that is in Ko-Bizen works and instead substitutes with wildness in an undulating midare that again brings up Norishige and Go Yoshihiro.

One extremely interesting aspect of this sword, and unique among Ko-Hoki works that I could reference, is the presence of an ichimai boshi (full "temper"). There are three others among the Juyo that show partially forming ichimai and this one is rather fully formed. Furthermore on one side the hamon rapidly ascends into the monouchi and proceeds through the boshi as a full temper.

Ichimai boshi of course is one of the major features of Go Yoshihiro, and this blade then further ties a knot around Masamune, Norishige and Go in shared styling and techniques. Ichimai is not a common feature at all and we expect to see it on Go, but here we have a blade predating him by centuries showing this feature. This would lead us to believe that other Ko-Hoki works since lost may have had this feature and this was the inspiration then for Go Yoshihiro as he worked closely with Norishige and Masamune, and came from the same province as Norishige. While Norishige was the one who most closely followed Ko-Hoki style, Go's style is very close to Norishige and so shares features with Ko-Hoki by logic. Seeing an Ichimai boshi come up on this blade was a shocker to me and I think made it a very special item because right here with this blade we can see the origin of the style of Go Yoshihiro.

I would tend to believe that with the age of Ko-Hoki and the fact that they seemed to be a bit less sophisticated and methodical than the Ko-Bizen smiths who followed them and eventually out-competed them, that the origin of Ichimai was either in wild experiment or accident. It's possible that clay coming off of the monouchi during hardening would create a zone of hard steel, but this would have to be carefully balanced and tempered out to avoid the monouchi to be subject to breakage. Because we don't see it very frequently, we need sword picture to assume that this was a feature that was very difficult to work out in an everyday object that needed to absorb harsh impacts. So while it may have originated in accident its spectacular look may have encouraged them to experiment and find ways to manage the hardness with resilience. Apparently in this sword they were able to pull it off since it has survived for about a thousand years and also bears a kirikomi battle scar in the ji (see slide #7) showing that it was not just something to hang on the wall or carry around the Imperial court in Kyoto and never be used. This was a rough and tumble warrior's blade, and survived to the present day and for this, we can be thankful and show a great deal of appreciation.

I could wish that this blade showed no flaws or issues with health, and so could you, but the reality for blades this old or even 300 years younger than this, is that their age and polishes they took over the centuries has exposed some core steel sometimes. We accept condition issues as part of them being ancient artifacts of a forgotten age that actually have no right to even exist in our millennium. Without constant care and worry this blade would be nothing more than a pile of rust, so that we have it as it is now is really a miracle. And should it have been kept in a shrine and never used and be left to us in mint condition, with its signature intact, and not a scratch on it from battle, then also it would qualify at Juyo Bijutsuhin or Juyo Bunkazai or at the very least Tokubetsu Juyo and cost far more than what it is available to purchase at now. Even the Dojigiri Yasutsuna has some faults in it, as does this Ko-Hoki and it is one of the Five Swords under Heaven. I try to make this a point of emphasis because many new collectors tend to overreact to flaws in Koto works and it is a matter that needs some education, perspective and understanding of the ancient nature of these works.

One other interesting note is that the nakago on the tachi omote where we would expect to see a signature seems to have been hammered out. I suspect that this once bore one of the signatures of a Ko-Hoki smith, but due to the ichimai boshi, in the Edo period someone hammered over the signature and tried to present this as a Go Yoshihiro. I'm not entirely certain but this area stands out with a very different texture, possibly though it's not large enough for two characters to fit. An alternaite explanation then is that this bore a one character kinzogan attribution of for Go. At a later date this may have been removed and allowed the blade to be properly attributed to Ko-Hoki. It's quite prominent in the first photo of the slideshow. Have a look and theorize away.

I really like this blade, and I think it's something important for someone who is interested in the Soshu school. At the very least for those reading these articles it will serve as a good learning example to see what sat in the mind of Masamune and Norishige and Sadamune and Go Yoshihiro when they lifted the hammer in their forges. This blade, others like it, were on their minds, and their attempts to emulate the Hoki masters of their own ancient history and to surpass them, is what gave us the heights of the Soshu tradition and in turn the pinnacle of beauty of the Japanese sword.

Ko-Hoki Katana OshigataKo-Hoki Katana Juyo

Juyo Token Katana

Appointed on the 30th of October, 1992

Katana, Mumei, Ko-Hoki


shinogi-zukuri, iori-mune, slender mihaba, relatively deep sori, chū-kissaki


standing-out ō-itame mixed with mokume, the steel is blackish and plenty of ji-nie appears


nie-laden suguha-chō to shallow notare mixed with ko-notare, gunome, ko-ashi, and many kinsuji and sunagashi, the ha widens on both side along the monouchi


widely hardened, tends to ichimai, nie-laden


ō-suriage, kirijiri, yasuri (omote) kiri, (ura) shallow katte-sagari, three mekugi-ana, mumei


Hōki Province was known since oldest times for its iron production sites, a circumstance that gave rise to swordsmith groups early on. The most famous smith of that province was and is Yasutsuna who is also considered as one of the most representative smiths from the early stages of the fully developed nihontō. The Ko-Hōki classification comprises Yasutsuna and his school, e.g. smiths like Sanemori, Aritsuna, Sadatsuna, Sanekage, or Yasuie.

This blade is an ō-suriage mumei katana that can be attributed to Ko-Hōki. It shows a standing-out kitae mixed with ō-hada and chikei, a blackish steel, and a very nie-laden hamon with ha-hada and plenty of sunagashi and kinsuji. The blade looks like Ko-Bizen at a glance but is a hint more rustic, an approach that is in turn typical for early Hōki works.