Jacques

Darcy only ever gave his opinion, and that opinion was never based on verified facts.

Sorry, but I don't practice the art of divination. The hamon seems to be based on notare which is a characteristic of Soshu den but I can't say more. We should know if the hamon is in nie deki or not what the size of the nie is, what the structure of the hada is etc.

Hum https://www.swordsofnorthshire.com/products/hand-forged-high-quality-chinese-tamahagane-clay-tempered-samurai-katana-sword

I will be very clear, it's impossible to determine the age of a sword without having it in hands. To my eyes it's a fake...

This lineage from Markus is more detailed

The link between Tomoshige and the Rai school has never been established, and this theory is not recognized.

eBay.... I never bought a sword without having it in hands....

An exemple to share ? Kasane is always mesured to the mune.

Yamato den = high shinogi

Obiously gimei https://www.samuraimuseum.jp/shop/product/antique-Japanese-sword-wakizashi-signed-by-mino-no-kami-jyumyo-nbthk-hozon-certificate/?srsltid=AfmBOooramjpL2uGeOLrUD0P28RwlYDsa4aUalfgD_SBsxJpnjvUi4dq

https://www.seiyudo.com/ka-020523.htm

NIdai Nobutaka

From Markus index of Japanese swordsmiths (Nihonto meikan translation) Kaneiwa (兼岩), Bunmei (文明, 1469-1487), Mino – „Kaneiwa“ (兼岩), „Nōshū Seki-jūnin Kaneiwa“ (濃州関住人兼岩) Kaneiwa (兼岩), Eishō (永正, 1504-1521), Mino – „Kaneiwa“ (兼岩), „Nōshū Seki-jūnin Kaneiwa“ (濃州関住人兼岩) Kaneiwa (兼岩), Eiroku (永禄, 1558-1570), Mino – „Kaneiwa“ (兼岩), „Nōshū Seki-jūnin Kaneiwa“ (濃州関住人兼岩), gunome-midare in nioi-deki or nie-loaden ō-gunome-midare to hitatsura Kaneiwa (兼岩), Tenshō (天正, 1573-1592), Mino/Kaga – „Kaneiwa“ (兼岩), „Nōshū Seki-jūnin Kaneiwa“ (濃州関住人兼岩), this Kaneiwa moved later in his career to Kaga province Kaneiwa (兼岩), Genroku (元禄, 1688-1704), Mino – „Kaneiwa“ (兼岩), „Nōshū Seki-jūnin Kaneiwa“ (濃州関住人兼岩)

According the Nihonto meikan Nagatsuna never signed Awataguchi Nagatsuna 粟田口長綱, I would think it's gimei..

Worth reading https://www.nittetsukou.co.jp/eng/karematuzawa/2.html

Slightly erroneous: sand iron is not suitable for blast furnaces, so ore must be imported. The tatara will continue to operate alongside the blast furnaces.

It's not just the hada that characterizes a smith or a school. Having said that, without having the blade in hand, I can't say anything - the photos don't show much.

The major difference between koto and Shinto is the way steel is made. In Koto, it's the swordsmiths who make it, but this is no longer the case in Shinto, which means that the steel loses the specific characteristics of each region and becomes uniform.

The third stroke on the left of the kanji Kuni is reversed, that indicates a work of the nidai.

If you are not in a very wet environment you can avoid oil. It's that i do for decades.

Kanji Kuni clearly says that it's the nidai.

I don't think it's sunagashi (too far from nioiguchi), I'd say it's a tempering problem.

Make your choice (from Shoshin's site) HIDEKUNI MEI-JI 1868 AIZU MEIJI HIRONOBU TEI-KYO 1684 YAMASHIRO/KII SHINTO HIRONOBU GEN-JI 1864 MUSASHI SHIN-SHINTO IYETSUGU KAN-EI 1624 YAMASHIRO SHINTO KANEHIRO KAN-BUN 1661 HIZEN SHINTO KANEKURA TEN-WA 1681 MINO SHINTO KANENOBU SHO-HO 1644 MINO SHINTO KANENOBU KAN-BUN 1661 MINO SHINTO KUNIHIDE GEN-ROKU 1688 OSAKA SHINTO KOBAYASHI KUNITERU (same as KUNIHIDE) KUNIMORI KAN-EI 1624 MINO SHINTO KUNITAKE TEI-KYO 1684 YAMATO SHINTO SUKEKANE (same as KUNITAKE) KUNITSUNA KAN-EI 1624 BUNGO SHINTO YUKIHIRA (same as KUNITSUNA) KUNIYUKI KAN-BUN 1661 BUNGO SHINTO MASAKATSU TEN-PO 1830 HIGO SHINTO MASANORI KAN-BUN 1661 ECHIZEN SHINTO MASAUJI KAN-EI 1624 BINGO SHINTO MOTOHIRA KAN-SEI 1789 SATSUMA SHINTO MOTONOBU SHO-TOKU 1711 SETTSU SHINTO MOTOOKI KEI-O 1865 AIZU SHIN-SHINTO MOTOUJI KAN-BUN 1661 MINO SHINTO MUNEKUNI GEN-ROKU 1688 MUSASHI SHINTO NAOHIRO KA-EI 1848 BUNGO SHIN-SHINTO NAOYUKI GEN-BUN 1736 BUNGO SHINTO NOBUSADA TEN-MON 1532 YAMASHIRO KOTO NOBUSADA KAN-EI 1624 HIGO SHINTO NOBUTOSHI TEN-WA 1681 HARIMA SHINTO SADAHIRO GEN-ROKU 1688 OWARI SHINTO SUKEMASA TEI-KYO 1684 OSAKA SHINTO TADATSUGU KAN-BUN 1661 YAMASHIRO SHINTO TADAYUKI KAN-EI 1624 BUNGO SHINTO TADAYUKI TEN-WA 1681 BUNGO SHINTO TAKAMICHI MEI-REKI 1655 OWARI SHINTO TOSHITOSHI MEI-WA 1764 CHIKUZEN SHINTO TSUGUIYE - origin obscure YASUKUNI SHO-TOKU 1711 SATSUMA SHINTO YASUMICHI KAN-BUN 1661 MINO SHINTO YASUSADA KEI-CHO 1596 EDO SHINTO YASUTSUGU KAN-BUN 1661 ECHIZEN SHINTO YASUTSUGU (same as YASUTSUGU) YOSHIMICHI(1) MAN-JI 1658 OSAKA SHINTO YOSHIMICHI(2) EN-PO 1673 OSAKA SHINTO YOSHIMICHI(3) GEN-ROKU 1688 OSAKA SHINTO YOSHINOBU KAN-EI 1624 YAMASHIRO SHINTO YUKINAGA TEI-KYO 1684 BUNGO SHINTO YUKIYASU GEN-JI 1864 SATSUMA SHIN-SHINTO

This is where the problem lies, we are only interested in the mei if the work is comparable to that of the smith being copied, and we have a very good example with Kajihei who was talented enough to imitate the work (hada, hamon etc.) of high-level swordsmiths, only a thorough study of the mei could allow to see that this sword was gimei.

You need to buy some books like this one https://www.amazon.com/Genealogies-Schools-Japanese-Swordsmiths-Markus/dp/3839183472