Shin-gunto Swordsmith Identification

First time user. I picked this sword up at the Tennessee Military Collectors show. I think the first character is "I" or "Ido" and the 3rd Character is "Sada". Can't figure out characters 2 and 4. Any help would be appreciated. Paul

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Sadatsugu

It is I-something SADATSUGU.
The I-something is likely a place name or a family name (I looked for it in O'Neil's book, but didn't find it).
The second kanji is KIYO/SHIN/JIN, but in combination with "I", I don't know what the correct reading should be. Maybe something like "ISHIN"...
There were at least 3 or 4 Sadatsugu's around the WWII time.

Pete

Agree, I have the same issue

Agree, I have the same issue with characters 1 & 2. Maybe someone else can shed some light on this. Paul