Interesting Japanese sword to ID

[Volovonok]

I am struggling to ID remains of a Japanese sword and would appreciate any advice on this matter.

The blade came with a plain plated guard which does not match with a description of any Japanese military sword. I was advised that Japanese officials in the occupied Korea carried swords with similar guards but those had shorter 650 mm blades while this blade is 730 mm long. 

The total length from tip to the end of threaded tang is 845 mm, blade is 20 mm wide at the ricasso.

Interestingly, the blade arrived with the mismatched scabbard it does not fit into. Though they appear to be of the matching size, the scabbard curvature is slightly more than that of the blade's.