The heaviest Japanese tank was basically a worse Sherman. It was also produced in less numbers than the KT.
It was also never used in combat, all Type 3 Chi-Nu were kept on the Japanese Mainland to counter Operation Downfall.
Easy, get rid of tanks combat, imply naval combat and islands hopping.
No more so called T70 crap. Their destroyers and subs were considered very advanced.
Microing Zeros and destroyers instead of tanks, great ideas for COH3.
CoH is focused on company level combat though, what you want is an entirely different game that would have more in common with Rise of Nations or Empire Earth style RTS.