Lemmy Lemmy:
It doesn't matter what defense force they had. There would be no casualties because the Japanese would not have resisted because they'd already surrendered!
Right, because they got nuked. That was the point of using "the bomb", to force an unconditional surrender without invading.
In the spring of 1945, Japan was militarily defeated, the military class just didn't want to admit it to the people, yet. They approached the US about surrendering but with conditions. The US position was unconditional surrender so that was a no go. By the time Hiroshima was bombed, the Japanese had been willing to surrender if they could keep their Emperor.
America wasn't interested because they wanted to try him for war crimes. When Japan didn't respond quickly enough, the US nuked Nagasaki. A surrender was brokered but Japan still got to keep their Emperor.
This was actually brokered, in part by the British who had a better understanding of the Asian mind and culture. They were the ones that finally convinced the US to relent on the subject of the Emperor. In return for this concession, the position of Emperor would more or less become a titular position and the people made to understand he isn't a god or demi-god, MacArthur was

(jokes)
This allowed the Japanese to save some face in surrendering, while giving the US enough wiggle room to still call it an unconditional surrender.
I will correct one thing I said previously, the BEST outcome for Japan would have been if Britain had been able to convince the US just a wee bit earlier.