A confounding factor with Japan is that the role of the Emperor (and by extension, the royal family) was very tightly entangled with the majority Shinto religion. Once the image of the Emperor got hijacked by the political leaders (who then decreed that whatever they decided on was the Will of the Emperor, even if the Emperor Himself tried to contradict them), to dissent was the same as blaspheming the Gods. Once that mindset set in to a good fraction of the populace, then there was no shortage of people who thought they would essentially go to Hell if they did not fight to victory or death--note the stories of soldiers who made suicide attacks when their unit was defeated.I'm not sure, I think (as in Nazi Germany) it was in the public conscience that acting in this way could not continue forever. To a certain extent, people were brainwashed into following ideology - especially in Germany's case, where after the death of Hitler and the invasion of the Allies from the West and Soviets from the East, the mindset of the populace became 'the game is up' - suddenly shame descended and ensured generations of Germans would find it hard to accept or justify the actions of their nation.
I can't second guess whether or not the Japanese people would act in the same way, but I think after the devastation of two atomic attacks, then a hypothetical third on the capital, would likely leave the nation on its knees - perhaps not in surrender, but in no way to fight.