New swords vs Koto swords; How much is anecdotal and how much is scientific

[jdawg221]

So reading through the forums, and talking to older enthusiasts(as well as reading literature), there is obviously an established notion that koto swords are just higher quality and better swords then shinto/shinshinto/gendaito/shinsakuto. Usually it boils down to activity in the jigane, "long lost smithing techniques", regional steels, or that they were made for battle. However, there has not actually been any actual testing done to see what makes certain swords better then others. Basically all of this information is anecdotal. For example, in suishinshi masahide's report on sword damage, much of his tales are based off rumors. There is not any note of any pre-existing kizu on the sword, or if they may have had a hagire to begin with. To add to this, survivorship bias could be playing a huge role here. Of course koto swords would be better when all of the bad koto swords broke with use. Shinto and shinshinto swords did not see any mass conflict that would thin their ranks(besides maybe ww2, but nowhere near the scale of the sengoku, nanbokucho, onin war, etc.), so a lot of the "bad" swords are most likely still out there somewhere. 

What do we know for certain?
Well not all shinto, shinshinto, or gendaito smiths made the same work. For example, Inoue Shinkai made both swords with chu suguha hamon, some of which are rather normal in their temper thickness, as well as wider gunome midare and notare hamon. Specifically in Ohmura's accounts, he talks about how Shinkai's blades performed badly. He mentions this repeatedly. However he leaves out what could arguably be the most important information: What temper line did these Shinkai blades have, and what kizu were present(if there were any). Another funny thing about Ohmura is that he has endless praise for Sue Bizen, Hizen, and Onizuka Yoshikuni blades ironically enough, but I will get back to that. Another good example of this variation in work you see in shinto and shinshinto swords is Suishinshi Masahide himself. Plenty of his early work is in toran midare, wide hamon that he would later go on to criticize, while in his later work you see alot more chu suguha. Another common point I see that is always brought up here is that the shinto swords and shinshinto swords were sold for their looks, not performance. Honestly this is the most ridiculous thing I have ever read on the topic, especially with the prevalence of saidanmei and the existence of wazamono ratings. Completely ignoring the slew of accounts of destructive sword tests that individual han undertook as well as individual smiths. Regardless of era, the majority of swordsmiths were trying to make the best sword they could functionally, while also making it artistically valuable. If this was not the case, every other contemporary of Suishinshi Masahide would not have followed his trend of reducing temper width for the sake of performance. Were there smiths that made swords which mostly server as art work? Of course, however one could say this is not specific to the edo period, especially if the definition of "art sword" is something with a wide hamon(which it usually is). Examples of swords made for use can be found in basically every province during the edo period. I will go back to Ohmura's fondness for Hizen and Yoshikuni. He specifically recalls accounts of soldiers with 30 yen(this is most likely military yen, currency produced during the war) Hizento being able to cut through barbed wire and ammunition belts without the swords breaking. At the same time he mentions Shinkai blades getting cracks the size of red beans performing the same tasks. For one, swords in general are not great at cutting through metal. Should they be able to do it without breaking? Yes obviously, but there is a very good reason most kenjutsu ryuha have very few edge on edge techniques. It is known to not be very good for the sword. Assuming the shinkai blades in question were harder, it makes sense they would get large chips when used against steel objects. This is not very indicative of the quality of the sword, as long as they do not develop hagire from doing so. A harder edge is known to chip easier than a softer edge, with the tradeoff being that the harder edge will hold a sharp edge longer while the softer edge will have to be touched up more often. Another interesting point when going over Ohmura's accounts is that there are very few cases of the shinto swords outright breaking. He lists the percentage of which they return to receive repairs, but even makes a note that most of these swords being returned were work of second or third rate smiths. He also includes an account of an officer who had a large oei bizen tachi in shin gunto mounts use it and get a large chip in the edge.

 

 

However none of these tests are scientific. Even Ohmura's accounts are anecdotal: he does not provide specific details, and there are not any control groups present and obviously the environment that these tests were recorded was not consistent. This can be said for all of the stories surrounding koto swords. We have similar accounts of blades from some smith breaking, of blades from another smith bending, while also having surviving examples of swords that saw use and held up nicely. However the lack of use that shinto and shinshinto swords saw does not somehow mean lack of quality. If they were made during a major conflict, I am sure you would have similar blades around riddled with kirikomi, shinae, or chips in the cutting edge. Basically the lack of these survivors does not mean that there would not be any. I know this post is kind of just a mess of thoughts, but just thought I would provoke some sort of retrospective thinking in other members of the forum of what constitutes as proof and what doesn't. 

 

Also I should state I am not trying to start arguments with people, more so promote appreciation of all nihonto, regardless of era that they were made. 

http://ohmura-study.net/133.html

 

[klee]

Great post @jdawg221

 

For me personaly, shinto just doesnt have any sort of appeal to collect.

 

I have zero doubt a shinto/shinshinto/gendai sword would just about break any elegant chu/hoso suguha koto sword. And the comparisson is also kind of moot since they were generally designed for different purpose with koto leaning towards toughness for battle vs armor and shinto having the freedom of not needing to make blades that can withstand armored combat

 

As a collector, I am heavily influenced by historical settings and the general mindset of that particular period. I am particularly drawn to schools/smiths associated with temples . Calm, rustic works that exudes power really speaks to me at a personal and spiritual level. To me that is artistic appeal in itself. The highly prized and flamboyant works like the ichimonji schools while nice to appreciate and study, isnt something I would ever collect.

 

There has to be something that connects with me historically and asthetically. So I dont think the term "better" should be taken on a functional sense but rather it having a greater appeal for collectors. 

 

And while collectors all have their own reasons to collect from a certain time period, the general trend in how swords are priced heavily suggest koto blades are most desirable 

[PNSSHOGUN]

 

[jdawg221]

1 hour ago, PNSSHOGUN said:

 

Ive seen that before, as well as the obata kabutowari with what I think was a yoshihara if I remember correct. It's pretty difficult to do, especially if you like nihonto 😂 

[eternal_newbie]

There's also the matter of scarcity. Who knows exactly how well a Masamune cuts compared to a Kotetsu? Not even a Shogun would waste a Masamune on the testing required to prove that; meanwhile Kotetsu was alive and well and producing blades regularly. All we have are anecdotes about such-and-such cutting through a lantern stand, or so-and-so chopping a helmet in half.

 

Worth noting that a handful of old masters did have their blades tested; in particular Shizu Saburo Kaneuji was ranked as ryo-wazamono and later upgraded to o-wazamono, and the first-gen Bizen Kanemitsu was considered peerless in cutting ability, even outranking his saijo o-wazamono peers like Magoroku Kanemoto and Kotetsu. Who knows how some of those other Kamakura/Nanbokucho luminaries might have fared if their blades weren't generally regarded as too precious to put to the test? Then again, perhaps their blades being too precious to put to the test was all the proof of their ability that the Edo-period connoisseurs needed.

[Lewis B]

Perhaps kirikomi might be an indirect measure of a blades ability to withstand structural failure. Hardly scientific but provides a degree of competency by the makers. They were fully aware of what manufacture methods leads to an effective and resilient sword under the harshest of battle conditions. Afterall it was in their interests for their patrons to return home alive. 

 

The Ishida Masamune has signs of a couple of massive impacts to the mune yet survived. So I'm not sure I fully agree with Kevin's statement "shinto/shinshinto/gendai sword would just about break any elegant chu/hoso suguha koto sword". Perhaps a late koto blade when quality of manufacture generally took a dive due to the increasing need to supply the Sengoku period conflicts.

Edited April 28 by Lewis B

[eternal_newbie]

1 hour ago, Lewis B said:

Perhaps a late koto blade when quality of manufacture generally took a dive due to the increasing need to supply the Sengoku period conflicts.

 

Also consider that koto blades have a somewhat unknown past. Even for well-documented swords, we have no way of knowing exactly how many shocks, hits, bends etc. they took before reaching us in its current state. If an old koto blade breaks after two cuts and a brand new (at the time) shinshinto blade withstood ten, is it that the shinshinto blade had superior craftsmanship? Or did the koto blade finally succumb after taking tens, or even hundreds, of such shocks on the battlefield (and having material removed via polishing and/or horimono)?

 

For that matter, what impact does suriage have on the structural integrity of a blade that used to be much larger? It's a well-known theory that many smiths in the Kamakura and Nanbokucho period were so concerned with structural integrity that they signed with shallow lines instead of deep chisel strokes to avoid creating stress points in the nakago. For all we know, this may be the reason why some blades were simply not signed at all despite being ubu - the customer demanded the maximum possible resilience, or the smith was determined to provide it because of the importance of the intended owner.

[OceanoNox]

It seems that swords become harder in the Edo period. Hamon width and shape (someone told me the issue is with nie or nioi) play a role, I believe, as well as niku, in the durability of the sword. 

Perhaps more informed people can chime in; it's my understanding that older swords have more niku than later ones, which are both harder and have slimmer edges. (right now, I just found out that Tawara Kuni-ichi's book on scientific studies of nihonto is available on the National Diet Library website, he did measure a few parameters of antique swords).

 

I want to add that there a few schools that do edge to edge, because it's better to chip a sword that can be replaced.

 

4 hours ago, eternal_newbie said:

For that matter, what impact does suriage have on the structural integrity of a blade that used to be much larger?

From a purely engineering point of view, it depends how it was done. If slow and without heat, probably not much. Rather, considering how kizu and inclusions would be weak points, a reduction in length means a reduction in possible weak points.

 

[Nihonto student]

A widely discussed and controversial topic where scientific truth will likely be difficult to come by, just to make a reflection:
Regarding the topic, much emphasis is always given to the changes in raw materials between the various periods and to the hamon based on the studies conducted by Masahide, but much less is said about the actual construction characteristics, perhaps also due to a real lack of reliable information.
The simple question I think many of us ask is how,  a blade forged in 1300 can be considered technically superior to a blade made today... a few weeks ago my father made a classic statement: "Today, cars aren't made like they were in the '70s, it's all plastic."
Regardless of whether you agree with this statement or not, it got me thinking about the concept of evolution. What rewards evolution in the field of production in general? Basically, time and money. If I can produce the same object at a lower cost and in a shorter time with better/same or similar performance, this will be taken as the new reference model. Today it would be impossible to think of reproducing a car body like in the 70s, the costs would be insane... I wonder, then, how much time was required to produce a blade in the Kamakura period compared to the Shinto period? What about the combination of hard and soft steel as at the beginning the awareness of the percentage of carbon was zero? What techniques were in vogue compared to the kobuse of the Shinto period? Without reliable sources on these answers it is difficult to reach a conclusion...

[chi fan wong]

mr kojima talked a bit about koto steel a bit in this article:

 

http://www.ksky.ne.jp/~sumie99/Masamune.html

 

the last paragraph, regarding a masamune....  "But still I have a question, if such a blade is good as weapon. Of course I know that, soft and tough edge is better than sharp and brittle edge in some situation."

 

so it seem that between koto and shinto blades, it is less about the difference in quality, but a difference in use and therefore a difference in structure.

[Alex A]

Kind of getting the impression some generalizations appearing.

 

My thoughts, just because Shinto period arrives and its more peaceful doesn't mean smiths went out of their way to make crappy unreliable swords.

 

Any Samurai would want a good sword, they were expensive when new.

[Hoshi]

Hi, 

 

Perhaps my perspective can help. 

 

I think the scientific perspective is a dead end. Why? Because controlled test conditions are impossible to create on historical swords ("too many variables that can't be systematically varied"). Research on Japanese steel and destructive testing on Google Scholar typically yield these ridiculously small sample studies, often with a no-big-deal Muromachi blade or two, sacrificed for metallurgic examination, which typically then leads the authors to make broad conclusions on Koto steel. This is over-generalization and unrigorous.

 

At the other end of the spectrum, there is the folk-science of Masahide's testing - I am somewhat more sympathetic to his approach. Try to cut stuff, make notes. Again, very limited. End of the day, nobody is going to sacrifice a meito on the altar of a Kabuto test cutting. 

 

All in all, the fact that Shinto blades have a higher average carbon content leading to brittleness is well attested, and even today's centralized tatara process suffers from overcarbonisation, which is the most common complaint of modern smiths.

 

But this is besides the point. If you want to understand the battle-worthiness of swords, you need to study the market, the method of warfare, and the needs of customers. This is fundamentally more interesting approach than attempting to misapply the scientific method: study the consumer demand profile and the market feedback mechanism. 

 

The market creates incentives, producers react to these incentives to make competitive products. Koto school that flourished produced in-demand swords. The main factor driving sword demand during the Koto period was battlefield feedback. Therefore, an efficient proxy for period-controlled, battle-worthiness is the popularity of certain Koto schools and maker that were in high-demand by the elite members of the bushi class. In other-words, if Oda Nobunaga or Toyotomi Hideyoshi took a liking to a certain smith, it's because the product got the job done, pretty was secondary, and they had nearly two centuries of accrued smith reputation to work with. Better, they either had first-hand experience, or second-hand experience from testimonials of their retainers or rivals. Nicknames at the time were simple and to the point: candlestand cutter, helmet cutter, etc. Collecting good swords as war booty, off the dead hands of rivals, was a competitive field at the time. 

 

What happens during Muromachi? Well, the demand profile changes. It's no longer about absolute battle effectiveness as it was during the Kamakura Golden Age, it's about getting production to be as cheap as possible to equip flocks of Ashigaru while maintaining a workable sidearm product that was used only in last resort. Different demand profile. That, and exporting swords to the mainland in high volume to quality-insensitive consumer to fund your armies. These were the early Toyotas, or the Shahed drones of today. It works and its cheap. 

 

And during Shinto time? Well, peace is upon the land, at long last. Sword smithing loses touch with battlefield reality. Imagine your arms industry producing weapons during peace time, without any adversary to provide feedback. And besides, all the people with money already have their ancestral collectible stashed away. But swords needed to be made in small quantities, this is where you start seeing hamons that feel extremely contrived, with painted tobiyaki and mount fuji impression rendered as hamon. Authorities knew this and of course a few swordsmith had access to their collections and tried making reproductions of Koto swords (Momoyama times, for instance), but it's a slow decline after that. By the middle Edo, the sword industry became so atrophied and the Shogun had to stimulate demand by providing honors and subsidies just to get some talented people moving into the field so it wouldn't completely die out, and a few talented smiths were found in Satsuma (Ippei Yasuo, etc) that genuinely stood out.

 

Things got bad, and everyone knew it. Customers started asking for "proof that it cuts" and that spawned an entire test-cutting industry which was profoundly misguided as the test cutting was performed exclusively on naked or barely clothed static humans in a standardized posture across standardize cut angles with a strange and unrealistic weight attached on the tsuka. That certification industry became very profitable not because of the test-cutting per se, but the side-hustle of creating snake oil out out of harvested body parts. A grim and decadent practice. 

 

So Masahide walks into this dying field, realizes something is deeply wrong, and sets himself up on a journey to rectify it and go back to the "old ways". During the Bakumatsu period, one starts to see swords getting longer and more brutal looking. This was a thing in Japan, the closer to civil war, the longer and more brutal the swords got. Nobody wants to be the one with the tooth pick when all hell breaks loose. Kiyomaro cracks the Koto recipes and produce secretly Sunno-To for the Imperialist faction as a side hustle. Naotane cracks it on occasion as well, creating the closest Bizen-mono Utsushi ever made. There is a genuine effort in making functional swords again, and demand is met by the samurai population getting prepared for the inevitable showdown. Money flows into the underground markets and civil war brews.

 

Nobody is looking for mount fuji as a hamon or a fancy Tadatsuna Horimono at that point. 

 

So what do we learn from all of this? Well, in the end, it is the desires of the customers that drive the market and product development, and the customer gets his desires from his current priorities. In the Kamakura period, this was about that solo duel on horseback against your sworn family enemy that you'd call out on the battlefield for a one on one in an effort to get his head and earn some glory for your clan. A blade severed by impact meant death and ridicule, and it made you and your entire clan look bad. And people watched and took notes. Battlefield effectiveness at whatever the cost was the goal. It was about having the ultimate weapon, the ultimate horse, the ultimate armor for those one-on-ones to grind up on the honor ladder and hopefully be rewarded by your Lord. I will skip the mongols and the effect it has on Bizen-mono, but things evolved quickly there as well as a result of pure feedback. During the Muromachi period, Ashigaru armies with cheap yari an arquebuses was the meta. No more heroic one-on-one for trophy hunting. Just bloody volleys, and once the Takeda Cavalry went down, it was the end of an era. War had forever changed its face, and demand would never be the same again. 

 

And yet, hard earned reputation during the Golden Age would persist to this day. 

 

I hope this helps, 

 

Hoshi

[Rivkin]

Suishinshi Masahide had a message - Edo period and everything associated with it was bad, it was better before and way better in late Kamakura. That was not unusual thinking towards Bakumatsu, whether the subject was economy, governance or sex life. How realistic is it when applied to swords is difficult to say. Overall Japanese ones are much harder than European and conversely are very prone to chipping. Great cutters with exceptionally short lifetime. You can chop a dozen iron nails with a saber and all you are going to get is the edge being shinier in places. But saber is not going to do nearly the same damage as Japanese sword.

 

If what you want is a cut from above against say human target, I would go with shinto. More consistent steel content and grain size distribution. More weight for the same size is not going to hurt you but makes the technique more forgiving. Will shinto be more prone to fatal damage under such conditions - this is not my experience and I have an issue finding any concrete evidence confirming it is so. Early soshu is just as hard at the edge as Sukehiro.

But early Soshu was battle proven... Its a big statement with not a lot of known quantities. Battle proven (very) often means we have X money, Y people and therefore we are going to make the weapons to fit the bill, nevermind all other considerations. Or it can mean we have one guy who survived a famous encounter 20 years ago and we continue making weapons according to his vision, until 20 years later people start believing in something else...

And if you are an actual weapon designer, being guided by soldiers is not going to yield a fantastic weapon. There are many reasons, including soldiers not realizing the tradeoffs between performance, reliability, cost and manufacturability, while navigating those is the key to being great weapon designer. A LOT of them will have memories of the fighting itself distorted to the point of being completely unrealistic. Or driven by a single event which drove them nuts.

So you are looking for a feedback of someone experienced, intelligent, calm minded, objective with knowledge of how the technology works. How many such people exist, especially since everyone who really fights rather than participates runs the risk of being killed which if not 50% then at least 10%

 

Back to swords, frankly speaking they all have nearly the same effectiveness, +/- 15%. Its not the kind of technology or environment where you kill 100 people and then elaborate on how it felt with say Bizen versus Soshu. In this case, "fashion" becomes important. Somebody with influence likes o-kissaki - everyone tries to copy and be cool. Then another guy says - its all hubris, traditional sugata is better, and in 10 years - nothing changed on the battlefield but we are back to shapes from 100 years ago.

Edited April 29 by Rivkin

[jdawg221]

22 hours ago, Lewis B said:

Perhaps kirikomi might be an indirect measure of a blades ability to withstand structural failure. Hardly scientific but provides a degree of competency by the makers. They were fully aware of what manufacture methods leads to an effective and resilient sword under the harshest of battle conditions. Afterall it was in their interests for their patrons to return home alive. 

 

The Ishida Masamune has signs of a couple of massive impacts to the mune yet survived. So I'm not sure I fully agree with Kevin's statement "shinto/shinshinto/gendai sword would just about break any elegant chu/hoso suguha koto sword". Perhaps a late koto blade when quality of manufacture generally took a dive due to the increasing need to supply the Sengoku period conflicts.

The thing is you can't really quantify what type of blows caused kirikomi, so even that is hardly scientific. Obviously if a blade survived with multiple deep kirikomi, it did its job well, but I guess the main point I was getting at is there isn't really a solid way to tell besides time travel whether something like an onizuka Yoshikuni or kunihiro would perform just as well in such a situation. Also, people like to waive around random mumei swords they own with kirikomi as if that is some sign of them surviving battle, but as a kenjutsu practitioner I can guarantee that at least some of those kirikomi could've been caused by martial arts use. This is different of course if a blade has solid documentation showing it saw usage however. 

[jdawg221]

6 hours ago, Rivkin said:

Suishinshi Masahide had a message - Edo period and everything associated with it was bad, it was better before and way better in late Kamakura. That was not unusual thinking towards Bakumatsu, whether the subject was economy, governance or sex life. How realistic is it when applied to swords is difficult to say. Overall Japanese ones are much harder than European and conversely are very prone to chipping. Great cutters with exceptionally short lifetime. You can chop a dozen iron nails with a saber and all you are going to get is the edge being shinier in places. But saber is not going to do nearly the same damage as Japanese sword.

 

If what you want is a cut from above against say human target, I would go with shinto. More consistent steel content and grain size distribution. More weight for the same size is not going to hurt you but makes the technique more forgiving. Will shinto be more prone to fatal damage under such conditions - this is not my experience and I have an issue finding any concrete evidence confirming it is so. Early soshu is just as hard at the edge as Sukehiro.

But early Soshu was battle proven... Its a big statement with not a lot of known quantities. Battle proven (very) often means we have X money, Y people and therefore we are going to make the weapons to fit the bill, nevermind all other considerations. Or it can mean we have one guy who survived a famous encounter 20 years ago and we continue making weapons according to his vision, until 20 years later people start believing in something else...

And if you are an actual weapon designer, being guided by soldiers is not going to yield a fantastic weapon. There are many reasons, including soldiers not realizing the tradeoffs between performance, reliability, cost and manufacturability, while navigating those is the key to being great weapon designer. A LOT of them will have memories of the fighting itself distorted to the point of being completely unrealistic. Or driven by a single event which drove them nuts.

So you are looking for a feedback of someone experienced, intelligent, calm minded, objective with knowledge of how the technology works. How many such people exist, especially since everyone who really fights rather than participates runs the risk of being killed which if not 50% then at least 10%

 

Back to swords, frankly speaking they all have nearly the same effectiveness, +/- 15%. Its not the kind of technology or environment where you kill 100 people and then elaborate on how it felt with say Bizen versus Soshu. In this case, "fashion" becomes important. Somebody with influence likes o-kissaki - everyone tries to copy and be cool. Then another guy says - its all hubris, traditional sugata is better, and in 10 years - nothing changed on the battlefield but we are back to shapes from 100 years ago.

Not so sure about the swinging sabers at nails statement lmao but yeah I agree pretty much with everything else you said. The Japanese sword in general lends itself more effectively towards a proficient user rather than a random grunt who will try to use the kissaki to pry at stuff. 

[jdawg221]

11 hours ago, Hoshi said:

Hi, 

 

Perhaps my perspective can help. 

 

I think the scientific perspective is a dead end. Why? Because controlled test conditions are impossible to create on historical swords ("too many variables that can't be systematically varied"). Research on Japanese steel and destructive testing on Google Scholar typically yield these ridiculously small sample studies, often with a no-big-deal Muromachi blade or two, sacrificed for metallurgic examination, which typically then leads the authors to make broad conclusions on Koto steel. This is over-generalization and unrigorous.

 

At the other end of the spectrum, there is the folk-science of Masahide's testing - I am somewhat more sympathetic to his approach. Try to cut stuff, make notes. Again, very limited. End of the day, nobody is going to sacrifice a meito on the altar of a Kabuto test cutting. 

 

All in all, the fact that Shinto blades have a higher average carbon content leading to brittleness is well attested, and even today's centralized tatara process suffers from overcarbonisation, which is the most common complaint of modern smiths.

 

But this is besides the point. If you want to understand the battle-worthiness of swords, you need to study the market, the method of warfare, and the needs of customers. This is fundamentally more interesting approach than attempting to misapply the scientific method: study the consumer demand profile and the market feedback mechanism. 

 

The market creates incentives, producers react to these incentives to make competitive products. Koto school that flourished produced in-demand swords. The main factor driving sword demand during the Koto period was battlefield feedback. Therefore, an efficient proxy for period-controlled, battle-worthiness is the popularity of certain Koto schools and maker that were in high-demand by the elite members of the bushi class. In other-words, if Oda Nobunaga or Toyotomi Hideyoshi took a liking to a certain smith, it's because the product got the job done, pretty was secondary, and they had nearly two centuries of accrued smith reputation to work with. Better, they either had first-hand experience, or second-hand experience from testimonials of their retainers or rivals. Nicknames at the time were simple and to the point: candlestand cutter, helmet cutter, etc. Collecting good swords as war booty, off the dead hands of rivals, was a competitive field at the time. 

 

What happens during Muromachi? Well, the demand profile changes. It's no longer about absolute battle effectiveness as it was during the Kamakura Golden Age, it's about getting production to be as cheap as possible to equip flocks of Ashigaru while maintaining a workable sidearm product that was used only in last resort. Different demand profile. That, and exporting swords to the mainland in high volume to quality-insensitive consumer to fund your armies. These were the early Toyotas, or the Shahed drones of today. It works and its cheap. 

 

And during Shinto time? Well, peace is upon the land, at long last. Sword smithing loses touch with battlefield reality. Imagine your arms industry producing weapons during peace time, without any adversary to provide feedback. And besides, all the people with money already have their ancestral collectible stashed away. But swords needed to be made in small quantities, this is where you start seeing hamons that feel extremely contrived, with painted tobiyaki and mount fuji impression rendered as hamon. Authorities knew this and of course a few swordsmith had access to their collections and tried making reproductions of Koto swords (Momoyama times, for instance), but it's a slow decline after that. By the middle Edo, the sword industry became so atrophied and the Shogun had to stimulate demand by providing honors and subsidies just to get some talented people moving into the field so it wouldn't completely die out, and a few talented smiths were found in Satsuma (Ippei Yasuo, etc) that genuinely stood out.

 

Things got bad, and everyone knew it. Customers started asking for "proof that it cuts" and that spawned an entire test-cutting industry which was profoundly misguided as the test cutting was performed exclusively on naked or barely clothed static humans in a standardized posture across standardize cut angles with a strange and unrealistic weight attached on the tsuka. That certification industry became very profitable not because of the test-cutting per se, but the side-hustle of creating snake oil out out of harvested body parts. A grim and decadent practice. 

 

So Masahide walks into this dying field, realizes something is deeply wrong, and sets himself up on a journey to rectify it and go back to the "old ways". During the Bakumatsu period, one starts to see swords getting longer and more brutal looking. This was a thing in Japan, the closer to civil war, the longer and more brutal the swords got. Nobody wants to be the one with the tooth pick when all hell breaks loose. Kiyomaro cracks the Koto recipes and produce secretly Sunno-To for the Imperialist faction as a side hustle. Naotane cracks it on occasion as well, creating the closest Bizen-mono Utsushi ever made. There is a genuine effort in making functional swords again, and demand is met by the samurai population getting prepared for the inevitable showdown. Money flows into the underground markets and civil war brews.

 

Nobody is looking for mount fuji as a hamon or a fancy Tadatsuna Horimono at that point. 

 

So what do we learn from all of this? Well, in the end, it is the desires of the customers that drive the market and product development, and the customer gets his desires from his current priorities. In the Kamakura period, this was about that solo duel on horseback against your sworn family enemy that you'd call out on the battlefield for a one on one in an effort to get his head and earn some glory for your clan. A blade severed by impact meant death and ridicule, and it made you and your entire clan look bad. And people watched and took notes. Battlefield effectiveness at whatever the cost was the goal. It was about having the ultimate weapon, the ultimate horse, the ultimate armor for those one-on-ones to grind up on the honor ladder and hopefully be rewarded by your Lord. I will skip the mongols and the effect it has on Bizen-mono, but things evolved quickly there as well as a result of pure feedback. During the Muromachi period, Ashigaru armies with cheap yari an arquebuses was the meta. No more heroic one-on-one for trophy hunting. Just bloody volleys, and once the Takeda Cavalry went down, it was the end of an era. War had forever changed its face, and demand would never be the same again. 

 

And yet, hard earned reputation during the Golden Age would persist to this day. 

 

I hope this helps, 

 

Hoshi

I mean the thing is the whole "mt fuji" hamon thing is very much a generalization. Not all Shinto smiths focused on pure aesthetics. In fact ohmura even makes note of this, pointing at that for the most part blades made in kyushu seemed to perform rather well. For example, take a shodai tadayoshi blade and compare it to a tadayoshi 8: yeah the shodai will have nice jigane and may have cleaner lines, but the overall sugata and features of the blade are almost identical. Same can be said with ishido smiths. Are there exceptions? Of course, there always are, but the blanket statement that all of them were made for art isn't really true. They were still carried regularly, and tons of people relied on them for personal defense. The priorities shifted. It's like taking a modern pietta Colt single action army and comparing it to the original: they're made for completely different purposes. Also I'm in the camp that Japanese swords are primarily designed with unarmored or lightly armored targets in mind to begin with. Yeah there are swords that may be more robust, but at the end of the day it's a sidearm. Like owning a Glock 17 and expecting it to do the work of an ar15. Yeah there were definitely flaws with the cutting tests, but there were also destructive tests done. I'm sure you've read the sesko writeup on the masao vs naotane test. 

[Rawa]

21 hours ago, OceanoNox said:

It seems that swords become harder in the Edo period. Hamon width and shape (someone told me the issue is with nie or nioi) play a role, I believe, as well as niku, in the durability of the sword. 

Perhaps more informed people can chime in; it's my understanding that older swords have more niku than later ones, which are both harder and have slimmer edges. (right now, I just found out that Tawara Kuni-ichi's book on scientific studies of nihonto is available on the National Diet Library website, he did measure a few parameters of antique swords).

 

I want to add that there a few schools that do edge to edge, because it's better to chip a sword that can be replaced.

 

From a purely engineering point of view, it depends how it was done. If slow and without heat, probably not much. Rather, considering how kizu and inclusions would be weak points, a reduction in length means a reduction in possible weak points.

 

Word on niku (meat) in general. To keep up.

https://japaneseswordindex.com/niku.htm

[Sukaira]

On 4/27/2026 at 11:22 PM, PNSSHOGUN said:

 

I had no idea katanas flexed like a whip on downward strikes like that. If you slow it down it really bends and snaps back right before contact.

[PNSSHOGUN]

That may have been a trick of the light/frame rate, in other slow motion videos of cutting the blade only flexes side to side once it contacts an object. 

 

 

[Julien]

I will add my two cents here (a bit far from the original subject, yet connected in my opinion).

First of all, I fully agree with @Rivkin, who expressed the point far more clearly than I could have.

Secondly, there have always been both good and poor blades, regardless of the period. The finest swords were those best suited to their intended purpose. It therefore makes little sense to compare, for example, a Kamakura tachi with a Kanbun-period blade later modified to fit a sword cane in the Meiji period.

Today, we are far from those times of warfare, at least in their traditional form. I believe that we now collect swords primarily for their historical significance (of which all blades are a part), their aesthetic qualities, and, for some people, the prestige associated to the blade/the smith. Since the original functional aspect of the sword is no longer central, a wide range of blades from every era, regardless of sugata, hamon, or hada, whether signed or mumei, and whether associated with a prestigious lineage, a temple, or an ordinary samurai, can be appreciated on their own merits. I believe that every smiths probably created at least one piece that could be fully enjoyable ! 

 

 

 

[MononobeNoTachi]

13 hours ago, Sukaira said:

I had no idea katanas flexed like a whip on downward strikes like that. If you slow it down it really bends and snaps back right before contact.

I have seen blades that had hagire have a helicopter-like forward spin when the hagire failed and the blade broke. It's why one must inspect their swords. The idea that a sword can have hagire and be "safe" for any kind of kenjutsu is a concerning label. 

[OceanoNox]

16 hours ago, Sukaira said:

I had no idea katanas flexed like a whip on downward strikes like that. If you slow it down it really bends and snaps back right before contact.

Could it be simply the way he cuts (I am assuming you are talking about the 3:00 mark). From slow motion videos, sometimes it looks like the blade bends downwards, but it's because the blade is more or less thrown before the hands. On the other hand, I have seen a bokuto bend upon strong impact (basically it straightens at the moment of impact before springing back into shape).

[Sukaira]

1 hour ago, OceanoNox said:

Could it be simply the way he cuts (I am assuming you are talking about the 3:00 mark). From slow motion videos, sometimes it looks like the blade bends downwards, but it's because the blade is more or less thrown before the hands. On the other hand, I have seen a bokuto bend upon strong impact (basically it straightens at the moment of impact before springing back into shape).

 

That white, forward bent line is the blade, if you slow down the video to 0.5x or screen record and slow it down even further it definitely flexes. But I guess it's not surprising as flexible blades are actually desired as the beginning of this thread elaborated on via Ohmura, it bends or it breaks. Also possible its just a really good optical illusion given the old video, but at 0.25x speed it is quite a convincing flex.

Edited May 1 by Sukaira

[OceanoNox]

I am very surprised it flexes in the air before the impact and in that direction. I expected it would flex at the moment of impact, but it doesn't seem to.

[Lukrez]

Thank you for the critical impulses and the many thoughts of others so far.

 

It is only a pity that the continuity of contributions tends to break off so quickly. (I also often hold myself back because I assume my opinion is of little interest. But every time I reconsider, I come to the same conclusion: writing things down primarily sharpens one’s own thinking—and just as importantly, new ideas can only emerge if everyone contributes. Exchange is what this community can continue to draw on in the future, just as we still benefit today from Darcy’s contributions, which so far remain unmatched in both quantity and quality.)

 

I am convinced that most of the points mentioned are valid. If one wanted to add another interpretative layer to the various theses and heuristics, one could invoke the Gaussian normal distribution as a model encompassing the work of a smith, a school, or an entire period: most blades are solid, some are quite poor, and a few surpass all others. In that sense, it is a principle of divergent randomness in time that ultimately gives rise to masterpieces.

 

Ultimately, however, none of us occupies a privileged epistemic position that would allow an unobstructed view of origins or functionality; at best, documented collections of opinions bring us a little closer. In every era, things happen that are beyond imagination—and what had to happen in order for certain developments to unfold often escapes our understanding today. If it were fully comprehensible, it likely would not have occurred in that way. My view is that the paradoxical strategies required to produce the outstanding blades of each period follow principles whose logic we may not even be capable of grasping.

 

It seems highly likely that in every epoch there were only a few individuals searching for and discovering novel, unadulterated materials and unknown techniques for the longevity and robustness of blades. Likewise, it appears plausible that certain schools experienced phases of rapid development and flourishing precisely when they were new and not yet “traditional.” Their gradual traditionalization often became the strongest predictor of their decline. This ongoing search, as a kind of blind reaction, increasingly solidified into tradition and in some cases evolved into something resembling a “corporate” structure—focused on accumulating and displaying markers of prestige. But not exclusively so: in the Edo period, there were undoubtedly sincere individuals striving to produce the finest blades within their means.

 

The Sagami school, for example, gradually developed into a fully rigid structure in which knowledge was strictly passed on to the eldest son, who assumed his place in the hierarchy regardless of his level of talent. Such a hermetic system did not allow for any fresh influx of talent or new influences. The focus was entirely on preserving the knowledge of previous generations. Due to the limited abilities of some successors, however, this knowledge could not always be fully reproduced and was therefore gradually lost.

 

Nevertheless, there may be some agreement that a turning point was reached during the Muromachi and Edo period: with the rise of mass production, mimesis, and the many forms of artistic heritage, a kind of aestheticism emerged that can be understood as the definitive intrusion of market dynamics into the production process—with all its advantages and disadvantages, but arguably with less reactive theory and less genuinely revolutionary practice.

Edited May 1 by Lukrez

[Jacques]

There is a misunderstanding regarding the difference in quality between Koto-period swords (particularly those from the Kamakura and Nanbokucho periods) and swords from other eras. Practicality is not the issue; a sword is a lethal weapon, and a kazu-uchi mono gets the job done. The difference lies in the artistic qualities of these swords.

[Sukaira]

I don’t think this is mind blowing news, but I think it boils down to the old saying “form follows function”. The smiths that genuinely tested their blades, both locally themselves and through users bringing them back from battle, and forged them to endure battle, created features (forms) that were born from the functions they had to perform. A gymnast’s tendons are like iron because they are forcing their body to hold insane positions on rings everyday. Likewise, swords created as talismans or art pieces are going to exhibit forms that follow the function of those needs. If you forge a sword with a bunch of sparkles and complex hataraki just for the sake of making it look really cool and dynamic,  chances are you might have lost some of the features that made it function well for  full spectrum battle.

 

Masamune was a master of nie, like ink paintings and so on - that’s great and all, but how does that translate to efficacy in battle or durability? Is the steel springy, durable and homogeneous or is it hard, brittle and inconsistent internally? I’m not saying I know which but I think the core of the question is, which swords are truly chasing function and which are chasing something that is removed from pure function. 

[Sukaira]

As to the main question of the topic - I think it’s hard to specifically quantify such a broad question. I lean towards “mostly anecdotal”  I think the general notion of koto is better functionally is probably not super scientific. Great swords across all eras, bad swords across all eras would be my take and the Gaussian approach is probably not far off. Much of the more scientific testing probably just proved what I said above though: form follows function - and when they tested old swords meant for killing and battle, gasp, they performed like they were meant for that. When they tested swords forged for looks, gasp, they broke as if strangely they were forged by smiths that weren’t living in dangerous times. Also agree with Jacques on that comment.

[MononobeNoTachi]

59 minutes ago, Sukaira said:

As to the main question of the topic - I think it’s hard to specifically quantify such a broad question. I lean towards “mostly anecdotal”  I think the general notion of koto is better functionally is probably not super scientific. Great swords across all eras, bad swords across all eras would be my take and the Gaussian approach is probably not far off. Much of the more scientific testing probably just proved what I said above though: form follows function - and when they tested old swords meant for killing and battle, gasp, they performed like they were meant for that. When they tested swords forged for looks, gasp, they broke as if strangely they were forged by smiths that weren’t living in dangerous times. Also agree with Jacques on that comment.

Ultimately unless we systematically tested every single nihonto to failure there isn't a real answer but if I had to choose between any of my collection I think I'd be choosing the blade with the least amount of kizu. 

[Lewis B]

49 minutes ago, MononobeNoTachi said:

 least amount of kizu. 

Impossible to know by casually viewing the blade as many kizu could be below the surface and would only be detected using specialised equipment with x-rays, ultrasonics etc. 

Edited May 2 by Lewis B