the problem with the jap tanks is they were lightly armored, undergunned and out dated. Sure you could add them in but whos really honestly going to use them vs a panzer or tiger or firefly sherman?
Id like to see some of the american WW2 tanks, british tanks and maybe even some french tanks. List below:
M18 Hellcat (yes, a Tank Destroyer... )
Charron B1
Renault R-35 (If lighter similar jap tanks are added)
M 40,41,42 (Italian tank, 75mm main gun)
SU-76 (yes another tank destroyer)
SMK (Interesting with 2 turrets)
M3 A1 Stuart
M3 A3 Lee
M.26 Persching
M3 A5 Grant
Churchill MK VII
Mk VIII Cromwell
Comet
Heavy tank Type 91
Sentinel
Anti-Aircraft Tank Skink
ALL of those would be better choices AHEAD of the "king" tiger... which had notorious breakdown issues and was deployed in horridly low numbers
*tank info care of
http://www.military.cz/panzer/index_en.htm