actually in the game are 5 factions; two axis and three allies.
for made more variety and balance can be good add the faction of japan for the axis
why can be good add japan?
in my opinion the add of japan ca be very good because japan ca be the nation in axis that can create masive units just like their enemys. This can add a lot of variety in the battles and in the style games.
Japan can have some abilities of assault for the standar units just like this:
-Charge: the japanese tropes charge to the enemys increasing his speed but making more vulnerable to the enemy fire
and some units or abilities can made kamikase attacks destroying the enemy but to them also in the process
-kamikase granade: the squad charge to the enemy with hand granades.
-kamikase plane: a japanese pilot crash his plane in the selected unit.
this abilities can add a big variation in the matches and made the game more entertaining
And i hear how someone say that add japan can't be historical because him will fight in europe. But actually the game battles are not historical
I saw some battles that US Forces are fighting in Stalingrado. This is historical? no, but any way this can happen.
so, why not add japan? with japan can be more maps for fight.
and in conclusion japan can be a good and feasible faction in Company Of Heroes 2