The reasoning behind that is their fanatical devotion to the Emperor.
When the Emperor said jump, the Japanese said 'How high?'
Following the Nagasaki and Hiroshima bombings the Emperor announced a surrender and the japanese armed forces *immediately* lay down their weapons.
That is why the bombings were unnecessary. A demonstration (Tokyo Bay was mooted, as it was easily big enough to drop the bomb over, while causing minimal casualties. Its obvious that such a demonstration would have caused the Emperor to surrender - leading directly to the armed forces surrendering also.
Why is it that people always refer to the Japanese sense of dedication when talking of potential casualties, while also ignoring the fact that that self-same dedication would make a surrender absolute?
If they were that dedicated, why did they lay down arms en-masse only when ordered to?
Surely if it was the bombing, rather than the announcement of surrender that caused this, they would not have waited two days ofter Nagasaki to lay down their arms?