The japanese military isn't unified at all. The services really don't like each other and really don't see eye to eye. And can only unify sometimes when they're talking about, you know, their right to control events or their right to receive piles of money. When it comes to specific things, they have total i reements.
The Asia-Pacific War of 1937-1945 has deep roots. It also involves a Japanese society that's been called one of the most distinctive on Earth. If there were a Japanese version of Captain America, this would be his origin story.