But not in the way people want them implemented. Japan was primarily a Naval and Air power. As far as armoured warfare, which Company of Heroes focuses on heavily, they would be worthless. Light Tanks were the mainstay of their armoured forces. Their land-based combat was based around extreme defense utilizing trenches, tunnels, bunkers, landmines, and boobytraps all set up before the enemy's arrival. That assumes they'd have half the map before you exit your base, or they'd be able to construct it rapidly with any infantry unit. That's not fun to play against, and coupled with the offensive capability of Wehrmacht or OKW would be wildly overpowered. Yet in a more conventional design, they struggle against even basic medium tanks, let alone upper-tier tanks like the Easy Eight or T-34/85. And fighting the IS-2 would be like trying to kill a Tiger with T-70's.
In short, you'd have to heavily fictionalise aspects of the Japanese Army in order to make them fun and effective against the current Allied armies.
I'm sorry but you're just wrong. Armored forces was virtually non-existent in IJA, what armor they had was used as infantry support, their land based combat was based around en massed infantry shock attacks grinding into attrition warfare if swift victory wasn't achieved. Their extreme defense as you suggested was a product of late war ad-hoc desperation initative rather than a regular military doctrine.
You have funny double standarts complaining about issue of realism in regard of building defenses when Germans players can build bunkers or Pak 43s in 10 seconds. Same with your complaint about realism of tanks, when US factions has no heavy tanks, and allies need to call in even the most commonly produced Shermans/T34s.