Ray Singer

The mei appears to be: Bishu ju Kunimitsu saku.

Agreed, Sukekane. My mistake above. Best regards, Ray

Bizen (no) kuni Norikane It is readable, don't do anything to disturb the rust on the nakago to improve the condition.

You can see an extended discussion below which deals with the evaluation of a tanto mei, and range of variation across the smith's atelier (the students working together in his shop, assisting and sometimes signing on behalf of the master).

Yes, swordsmith mei did vary from one sword to another and there is an acceptable range of variation within authentic examples. Some swordsmiths are known for this, for example shodai Tadayoshi. And also yes, evaluating the workmanship is a part of the shinsa process, in addition to judging the mei (inscription). However, you would not expect to see a legitimate Naotane mei so radically different from the juyo example above with an identical date. And there is a crudeness in the execution of the mei that raises doubts compared with legitimate examples from Naotane and his students.

This is what I provided for the date. 嘉永五壬子年 - Kaei 5, mizunoe-ne (zodiac date for 1852)

It is possible the next kanji is Tsune. Bishu Osafune Tsune__. Several smiths used this kanji including Tsunehiro and Tsunenao. https://nihontoclub.com/view/smiths/meisearch?type=All&mei_op=contains&mei=備前長船恒

I replied to you on reddit. My comment there is repeated below. Wonderful find. This appears to be a Nanbokucho period or earlier tachi, signed Bishu Osafune __ (the remainder of the inscription is not readable in the photos, however please do not do anything at all to try to improve the visibility of the inscription). There may have been a date on the other side of the nakago, not presently readable. Do not try to remove rust on the nakago (tang), or to clean or polish the blade in any way. It has every indication of being a valuable sword. Best regards, Ray

Hopefully no one here will bid on this. It is certainly not an authentic Yasukuni-to. At best, it is a showato arsenal blade, doctored up with a gimei and frankenstein'd koshirae. i'm sorry to be so blunt, and I don't like to comment on active auctions, but this is one of the worst things that I've seen posted to the group.

Ishihara Yoshisada. A WWII era showato smith. This one has a Seki arsenal stamp. It is not traditionally made.

Jay: Bishu in the inscription indicates the smith worked in Owari. Masayasu is his art name.

Bishu ju Masayasu saku, dated 1942. https://www.google.com/search?q=mano+masayasu+site%3Amilitaria.co.za&rlz=1C1YTUH_enUS1164US1164&oq=mano+masayasu+site%3Amilitaria.co.za&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIHCAEQIRiPAjIHCAIQIRiPAjIHCAMQIRiPAtIBCDYwNDVqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8

I looked on a different screen, and it does look like 兼常 (Kanetsune). 武州神田住藤原兼常 (Bushū Kanda ju Kanetsune)

The nakago itself is slightly suriage (the end has been reduced) however the mei is fully present. There appear to be two kanji after 'ju'. The first is definitely 'Kane'. The last kanji is unclear as it is been washed out with the light. I would suggest trying different lighting conditions so that the glare is not so intense in that area.

The kanji with three horizontal strokes is ju (住), which wouid typically be followed by the swordsmith artname, clan + artname, etc. The name itself is not shown here, but unless it is an unlisted smith this is likely Bushu Kanenaga or Bushu Kanetsune (one of two generations). Even if the inscription is corroded , it is still worthwhile to try and show us a photo of the entire inscription top to bottom in one vertical image. Sometimes just a couple of strokes can distinguish between one or another possible craftsmen (in this case, determining if it may be Kanenaga or Kanetsune). Not making any guarantees, but as you are asking for assistance with a translation it is helpful for us to try and evaluate everything. And one additional note, please don't do anything on your own to try to make the inscription more readable (no chalk or cleaning). This may seem obvious and I am sorry to mention it, however I've seen a number of cases where new collectors have tried some amount of cleaning to improve readability on an inscription that was already readable, removing the natural patina and destroying the originality of the mei in the process.