Here's a thread on a "kamikaze dagger" from NMB, 
http://www.militaria.co.za/nmb/topic...knife-special/ 
Battara, I would not be surprised if your knife was intended to be mistaken for a kamikaze tanto, but without the investment of a properly faceted shirasaya.  It would be interesting to see the  nakago, to determine if the short blade came from the tip of something longer.  There was a sword shop in Tokyo which managed to stay in business all through the Occupation sword ban (and still is, last time I looked), selling stuff assembled out of their leftover stock of gunto parts, to GI's and other visiting Westerners.  Among other things, they learned to reproduce a really mean USMC mameluke.  
