Rivkin

I like what I see but i am away from books. Does look like early Muromaci Bizen and i personally would be a bit more comfortable with 1440. Signature is well done

There are plenty of activities, but the only way there is such a significant difference for a blade seen from above with light on a side and seen at an angle is if nie is below certain size... or there is a huge polishing issue. The latter should not be the case here, so nie size is small.

Very strong jigane, but if one don't see hamon on top-down photos of eirakudo it means its nioi with maybe ko nie.

Thank you very much, that probably it!

I read "ko" followed maybe by tsugu?? Any help would be greatly appreciated. Its an interesting blade I picked up and I will try to post more photos later...

I appreciate the vote of confidence, but I see the same - there are some issues, though shintetsu like this is probably not a great problem here - it does look like a typical sue Bizen in suguha.

With such boshi I would say Tametsugu appears as quite possible outcome.

With such strong nie Naminohira excluded. This is most likely Uda. I would say Yamato Shizu or Shikkake are distant, but possible. Timewise I would lean towards early Muromachi. There is also possibility its early Kaga Fujishima, which is basically other way to interpret Uda features.

It has some Soshu to it, but Yamato also feels very strong here. Uda is a possibility. Tametsugu is optimistic outcome.

The magnification/resolution is unfortunately not there. What is seen is that hada is masame dominated, hamon is ko nie to nie deki, suguha with a bit of gunome, midare. Definitely koto, but without high res pictures its hard to say something more specific. Nakago sustained significant damage which will scare a lot of people to think its saiha, but the work does not lean this way. It can be Naminohira. Or Yamato shikkake. Finally, Uda is definitely worth consideration. The most optimistic outcome is Yamato Shizu. Period can be later... High resolution would be nice, also boshi [!]. If hamon widens towards yokote its a common Muromachi trait. In general it feels like the photos are good enough to identify, they've just been downsized until not much is seen...

I think you are right. I scanned the sword descriptions pdfs I stored away and got roughly the ratio 12:1:3.5... With a caveat that my pdfs are obviously not representative and if anything they probably over-represent Kunzan and potentially Kanzan. If I take Tanobe-sensei's sayagaki at 3000 that would be 600-1,000 for Kunzan and 25-36,000 for Kanzan.

Hard to estimate because its a non-random selection which tends to cluster around upper TH and Juyo, but one can estimate the ratio between three using just Juyo swords and then guess the number of sayagaki for one of them getting all three. My pure guesstimate would be about 1,200 for Kanzan, 100 for Kunzan and 300 for Tanobe sensei.

Any proven DYI recipes for getting rid of stupid kimpun mei without damaging old and nice patina or its polisher only task?

They never really matched Kongo jigane. O-Sa went Rai first, then Sa went Soshu with very fine jigane and hamon which is sort of choji or suguha nioi with very strong belts of nie. In Muromachi after Oei it mostly reverted to weird provincial Yamato.

Edo period, lots of acid.