Uniquely shaped GUNTO for Crew, Ryakushiki Style, Late WW2, Japanese Officer Sword

This is a very unique gunto.

It has the simplest exterior.
It appears to be a Shirasaya with a ring and leather cover attached.

The Tang cannot be removed.

Its short overall length and the absence of a Tsuba suggest it is a gunto intended for a crew member.

Signature : Unknown
Nagasa : 510mm (20.08 in.) 
Sori : 18mm (0.71 in.) 
Total length : 750mm (29.53 in.) 
Motohaba : 28.9mm (1.14 in.) 
Sakihaba : 21mm (0.83 in.) 
Motokasane : 7.2mm (0.28 in.) 
Sakikasane : 5.2mm (0.20 in.) 
Total Weight : 863g