You are leaving out the historical context of hyper violent insane independent action for honor mindset of the soldiers within the Imperial Japanese Army and Navy (IJA/IJN).

This culture of insubordination included a widespread belief that they did not to have obey civilian commands, and is largely responsible for ground level soldiers deciding on their own to kick off the war in Manchuria.

It's entirely reasonable to envision a counterfactual version where either one of, or both the IJA and IJN refuse to surrender, or even just large contingents within either.

I'm not saying this to invalidate anything you've said, but I do think it's highly relevant context when considering any alternative ways that could have gone.