World War II Japanese Dagger

Howdy!
Wondering if any of you military buffs might know what this is WW II item is called? It's a nasty little dagger (I guess you would call it that) that was brought home by an uncle who I believe was in Burma. The simplistic style of both the weapon and the sheath made me think it might have been carried by a mountain tribe. I searched and searched and found nothing until I came across the picture of the Japanese soldier, and there it was! A very simple but very deadly side weapon, just stashed in a belt or a sash. It really is wicked. If you can't read the tape in the picture, the whole sheath is 23", the dagger with the handle is 19 1/2", and the blade is 14 1/2". The point is WICKED sharp, and the first 8 1/2" is a "bloodletting" style of blade, 1/2" wide, that turns into a square shaft for strength. The sheath is decoratively wrapped in leather (possibly plant material), and the blade sits in wood. (?) Sad to say, I believe that there remains the DNA of the last victim(s) that were dispatched. Any info would be greatly appreciated. Thanks.