Definitely looks like a period Japanese naval officer's dirk.
I agree with Blitzkrieg.........!
Very nice Dirk
We are the Pilgrims , master, we shall go
Always a little further : it may be
Beyond that last blue mountain barred with snow
Across that angry or that glimmering sea...
Overall looks OK.
Maybe you can make some close up photos (handle,front nad back) because Menuki does not look like naval Shin Gunto typ ?!