I've had this Type 3 Gunto a while. I always thought it was unmarked, but recently checked again with better lighting. Now I see some faint marks peeking out from behind the rust.
There isn't enough exposed to ask for a translation. Would it make sense to carefully clear away the worst of the rust buildup to expose the signature, or would it be better to just leave it alone (antler?)
Not sure that this is patina worth saving, but maybe there's nothing to be learned here anyway.