To add to this, just look at how many ****** from both sides fought in the Battle for Okinawa. Then compare the casualties for both sides but pay close attention to the Japanese numbers.
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Estimated 67000-77000 plus another 20000-40000 conscripts. And out of those and estimated 77000-110000 were ******, 7000 captured, plus another 40000-150000 civilians were ****** or they commited suicide (more on that in a bit). That is damn near 100% dead and only 7000 captured (how many of those were willing?). What does that tell you about their willingness to surrender or fight to the last man? what if the results had been the similar for the invasion of Japan? 90-100% casualty rate for soldiers and who knows how many civilians ****** (because they took up arms) or commited suicide?
Read "The Burning Mountain" by Alfred Coppel. It is fiction, but it tells a story of how an invasion of Japan might have looked like. IIRC it used actual declassified documents as source materials so its not like the author was pulling everything out of his ass. The story is told from both sides and from several different perspective.
EDIT: another thing too if i remember my history is that despite the Japanese losing they would not surrender because of what they were offered in the Potsdam Declaration. The Japanese wanted to surrender under terms favorable to them, but the allied countries pretty much said these are *our* terms and they are not negotiable.