Someone has offered me what looks, in some regards to be a gendaito gunto. But it has been messed around with.
Also, whenever I have come across 4 character signatures, these have tended to be late war model Showato, oddly / sometimes without any acceptance / arsenal stamp.
Anyway, the mei;
I believe this is a badly written / inscribed (unknown) Kane Nobu saku (not the famous Kanenobu), but I can not fathom the first character. For me the 3rd character is so badly done, it could be "Sa", but after much reflection I think not.
Can anyone help with this terrible "hand writting"?