Design project for a delta wing fighter by French designer Roland Payen for Mitsubishi dating from 1938. Apparently the French government authorised release of the plans to a foreign power because they believed the concept to be of little aerodynamic interest. I believe this aircraft was to have one or two radial engines buried in the nose but I am not certain, there's not much information available on it.
The spherical recess underneath the model is for mounting it on a 4.5mm (.177") BB.