I agree, it is probably some kind of Prototype.
It looks a bit like a Ki 67 "Peggy", but there are large differences.
In fact, the protruding bubble cockpit and lack of observation in the nose, or any sponsons on the sides makes this unlike any Japanese aircraft I am familiar with in WWII.
It even resembles the P1Y1 "Frances", which is what I might guess except that once again the Francis had an observation and gun position in the nose, and it is to elongated.
I also can't identify it as anything British, Italian, German, or US. The cockpit and nose combination is completely unique to anything I have seen of the period.