In 1/56th, outside of a few manufacturers you're stumped. Trenchworx have a line of early war Japanese vehicles which are probably more up your alley than Company B or Warlord, as those two are more mid/late war focused.
I've found that conversions are the way to go. The Japanese re-used a lot of parts between models, so whilst you may not be able to find the pre-war vehicle, you may get away with buying a descendent of it and hacking it up a bit (I'm in the process of turning a Chi-Ha into a Ho-Ri II by extended out the track assemblies).
You're probably better off just sticking with Trenchworx and having a few holes in your collection than scratchbuilding though.