The trick will be to search using the proper names of the aircraft;  The Japanese don't call their historic aircraft by U.S. code names--there isn't any 'Sally', and certainly not a 'Dinah.'   They're still kind of testy about that. . .
     There is a Ki-21 Type 97 available from BR planes;  Ki-67 Kais and Ki-46s ("Army Type 100") will be difficult to find.   Try VB planes via Sim-Outhouse for more off-the-wall types.
     Yashico Cool is one site with substantial actual Japanese content;  His downloads are code-protected, so a password is necessary from him via Email.