The US actually didn't want to invade the Japanese home islands. Dropping the A-bombs was an attempt to avoid that bloodshed. And Japan didn't really unconditionally surrender. They surrendered on condition that they keep their Emperor and also apparently that they wouldn't be hung for war crimes.
Germany was the one that didn't surrender, and the Allies destroyed it and then took vengeance on the German people.
The US actually didn't want to invade the Japanese home islands. Dropping the A-bombs was an attempt to avoid that bloodshed. And Japan didn't really unconditionally surrender. They surrendered on condition that they keep their Emperor and also apparently that they wouldn't be hung for war crimes.
Germany was the one that didn't surrender, and the Allies destroyed it and then took vengeance on the German people.