Sad treatment for a beautiful piece.
Now you should invest money to sent it back to Japan to a professional restorator, cleaning and handling rokusho for a good niage patination.
Never see this before.
Haian period tsurugi / ken?
46,3 cm nagasa
Sukashi carving - very interesting.
Maybe someone knows more about it?
For me it could be the Kusanagi-no-Tsurugi
The only thing that worries me is the condition of the metal saya. It looks as though it was stored in unfavorable, humid conditions. You should consult experts to halt the rusting and preserve the piece. This has a huge impact on the sword's value.
Hi Joe
congrats, you hold the holy grail of collecting NCO swords in hand.
Don't clean it. Don't rub it. Only oil slightly the blade. I would not dissamble it.
He looks very young for a seargent major.
"In the Imperial Japanese Army (IJA) during WWII, a Sergeant Major (Sōchō) was a senior non-commissioned officer. Because the rank required significant military experience, Sergeant Majors were typically career soldiers between 30 and 45 years old."