News flash, the Japanese didn't care about "Hirohito's surrender". They were still shooting GI's, Chinese, etc.
Some were, though not even close to being a majority.
The key to the nuclear bombs going off was not the killing of thousands of people, but what the emperor did.
Up until that point the emperor was a god, literally. He was thought to be the son of the gods. His word reigned supreme. You did what he said. Or you were dishonored and killed yourself because of it. No one spoke to the emperor except the extremely close advisors.
What the bombs did was make the Emperor come out of his palace and address the nation on the radio. The emperor had to tell the nation that he was not a god, and that fighting the war was not worth the lives of anymore japanese.
The closest analogy I can think of would be if Jesus Christ was alive today. Imagine that he goes about preaching, doing miracles and claiming to be the son of god. Then one day he goes on TV and admits that he is not the son of god, and it is not worth it to follow his teachings.
You would be stupefied to the point of inaction.