Rivkin

Usually I feel this answer does not add anything except shifting the responsibility, but... eventually this blade will end up with shinsa anyway. In this sense its all the same what is said here. It has potential. I am not even close to be competent to be judging tester's signatures, especially with such photos. Submit it.

Precisely - if only hadori is seen, it means either that hadori is very heavy or the hamon does not have any nie. The problem is that some of the photographs are from above, some taken at an angle. Both cases look nearly the same, but if you put the contrast to the max, there is some nie. Which suggests its very hadori heavy and most likely its ko nie without any large nie crystals. Otherwise you would see significant difference at different angles.

Treating it as gimei: Around Tembun(?), weak hada, poor polish, hamon suffocated by hadori.

To keep matters fast and simple - its not, the chance of repapering today is 10%.

I don't know how true it is, but I've seen those sold in Japan as Ezo (Hokkaido) style, sometimes with red lacquer in horimono.

Large, uneven sori, hada devoid of activity except a few large laminations, dull suguha or notare based hamon - 95% of saiha looks this way.

Saiha, polished to the end or born ultra-deficient. Signatures were done relatively not long ago and the objects chosen for "improvement" were of near zero value.

2 are dead Muromachi blades and possibly saiha with crazy signatures. One is interesting ("ko-Bizen"), however utsuri possibly was acid accented. Certainly was submitted for modern papers, got something lesser as appraisal. The question is how much lesser? Still can be an interesting blade, but commercially is not viable.

Particular shape is a bit hard for me to judge - can be the end of Muromachi, can be shinshinto, I don't think though its koto. But the general rule is that unsigned tanto with very few exceptions (early Soshu) are very seldom top tier work, though I've seen couple of decent or even good shinto examples, to my surprise. But there plenty of non-descript late Edo work which is not impressive. Unless there is a strong statement suggestive otherwise (and I don't see it here), I would not expect much.

The nakago is Edo but for the rest would prefer to see images with light from a side. If light is from above, even if its just room fixture, it flattens hada and whitens hamon. There is only one very specific position above which is ok for taking pictures.

Tsuda Sukehiro is a famous name, and there is nothing in Meikan about his student Masahiro signing Sesshu so I would doubt the source. Jigane is not Osaka. Work tries to be a bit Soshu.

I would simply put a link to the sale, especially since the photos got compressed quite a bit. Its even hard to say what is it - Naminohira?

Basic thing to check is what are the cheapest items in the store. Price is a relative thing in collectibles, more so than in other fields. Otherwise - sue Bizen can be great. Kiyomitsu and early Sukesada in particular. I don't think it applies here. Jigane is rough. Middle one at least carries some fun.

Discussions about utsuri tend to follow the same pattern - there are few postulates and there are groups of people defending each. The basic problems are: a. There is no per se scientific analysis of utsuri which clearly demonstrates what it is. Unfortunately I am not aware of someone taking an old Bizen blade, looking at the structure and saying - within utsuri we have (a), outside we have (b). In blades without utsuri we have only (b). Repeat to confirm. Instead there are many people making conjectures about what (a) should be. Basically like wootz studies used to be around 1990-2000: there were couple of blades analyzed, but 95% of information in publications were conjectures which went like "since wootz got to be superior because otherwise why would they do it, it is probably nano-fulleren-carbon etc.". Reality is most old ironworking is about trying to adapt to very severe material/temperature/timeframe constraints. The lost knowledge of quantum-coherent-supersteel is associated with professors submitting a paper to nature. . b. Related to previous point - no clear experiment analyzing what is jifu utsuri, midare utsuri, Muromachi bo utsuri etc.. Is it the same (a)? Different? Is hardening or composition what determines jifu/midare/bo structure? c. Modern methods of making utsuri have one purpose - to make utsuri. Hopefully looking like the old one. The simplest way to do it is a fine done acid etch, but its cheating and yes, its mostly visible from the top. Still its popular in Japan. Real deal usually needs to be looked at from a side. But again - not always. So does it mean if I manage to make utsuri today I know how ko Bizen did jifu utsuri? Open question. Plus people who made really good utsuri in the past 200 years tended to be a bit silent about the details. So to summarize - in wootz only when people did the analysis of 30+ blades it became apparent what the "real wootz" is (except there are many still arguing that it is not). Studying utsuri basically means sacrificing (non-destructive testing is not used in professional iron metallurgy) a few old blades, targeting utsuri versus non-utsuri areas. I did such study with a single Muromachi Uda blade and basically it was very dirty steel with visible composition variation which even without hardening would produce some "utsuri" during polish. Is this universal? No, I don't think so. But I do suspect that considerable portion of utsuri variery is because of composition variation multiplied by hardening effect.

Sorry - I am not a title's guy, so I am still not convinced it involves multiple, beyond maybe two, quenchings. Otherwise its a matter of what's defined as thermocycling. Can easily imagine I am operating on a different terminology than knifemaking.

Ok, so what is defined as thermocycling? Multiple quenchings? Above two - would love to see an example. If its not quenchings, then we are probably in multi-stage annealing territory? Which is a big topic of its own, with often multi-days timeframe... and I don't know if it relates to utsuri or not, and how much use it saw in Japan at all.

Twice quenched - possible. Not under any circumstances, but under some, possible. More - runs into some fundamental issues. By the same token, annealing is common as part of technological process. Quenching is somewhat common. Thermocycling... No. For test purposes on couple of samples - yes, as part of production process on a shipped part I am struggling to image the circumstances. Can be micrometer scale laser-induced hardening - basically super exotic. Can be hair splitted by calling "micro-thermocycling" almost anything, anything heats and cools a little bit, but then its not a discussion about technology. There is a common thing which is multi-stage annealing where you heat the sample and then slowly cool it off - but "heat" in this case is done slowly and not to very high temperature. and cooling is done much slower. No quenching, no heating red hot, the purpose is gradually reach the ground state without much martensite or stress.

Repeated quenching? I must be missing something. There can be an argument for two separate quenching procedures under some circumstances, but that would still be not too common.

I doubt someone would use thermocycling. Especially on a "production" and not a single "test" blade. There might be sense that in a steel with drastically varied carbon content you might do double quenching with different temperature gradients since the optimal point is going to be different.

Not something I personally did but yes I've known people doing it.

Basic problem as I see it is the same as with wootz. There are popular smiths who claim to reproduce wootz and lecture extensively on their method. Their wootz looks... problematic. There are a few whose wootz is close to historic examples. They are not telling too much about how they do it. It is very clear that 90% recently (Edo+) steel even though its from tamahagane, it has very different thermal conduction properties compared to koto and it just does not harden similar to how koto swords did. There were always a few smiths who managed to produce hada which looked quite a bit more koto and a few who could produce reasonable utsuri. They are not too open about the secret sauce.

I don't have much to add to what already said, maybe a couple remarks. First if you show the entire blade it might be possible to tell if its early shinto or Kambun. NBTHK is generally very stingy in terms of information, saying the bare minimal. It would be also interesting to see the boshi, but I guess its sugu-boshi. I've seen works of lesser smiths while not dated but with smiths generally associated more with 1580-1590 production timeline classified as shinto if the blade is in shinto style - dense hada, sugu boshi. Its a good koshirae. Its style is more or less 19th century popular, and mother of pearl you see considerable more often in the 19th and more so early 20th century. There are earlier, Ryukyu inspired examples, but they are rare. The same and wrapping while well done appear somewhat fresher and could be 20th century. If you want you can associate the symbol on kojiri (arrows with a wheel... I am certain there is a proper name for it... dharmachakra?) with a kamon and find the one matching in one of the books - and this might be a connection.

Since once I was investigated for "Scythian Supremacism"... few realize how powerful we are. No one bans akinakes. No one has the guts to openly question why. Ninjas are just the beginning.

Its a style which unfortunately exceptionally hard to judge. Even in hands and in good polish. If you want to be super-optimistic, pursue Kamakura Rai Kunitoshi kodachi option. I don't believe that's the case, but... Otherwise its Muromachi uchi-gatana. Can be a variety of schools, we don't see jigane unfortunately and that's the main distinguishing factor... Ryokai, Fuyuhiro. Mihara would probably have longer kaeri or altogether different boshi, Enju tends to be quite different in Muromachi and also boshi, Zenjo is possible though not the most typical. At times Kaga can also be considered. Lots of options and not much difference since mumei Muromachi pieces in 80% of cases are judged with thinking "its more or less the same".

Taking pictures of nihonto during daylight does not work. Evening, confined lightsource, blade on the table, camera and light source positioned for maximum effect. As of now sugata looks like Muromachi uchigatana. With such curvature to be Kamakura you basically have to aim for kodachi... that does not look like a perfect match.