If I know the history correct Japan actually did get conditional surrender. The USA wanted unconditional surrender which the never got despite dropping 2 atom bombs on cities which were not really military targets.
"We hereby proclaim the unconditional surrender to the Allied Powers of the Japanese Imperial General Headquarters and of all Japanese armed forces and all armed forces under the Japanese control wherever situated."
That's a quote from the Japanese Instrument of Surrender.
Japan wanted to keep the emperor of japan this is why they wouldnt unconditionally surrender. I was under the impression that they got to keep the emperor thus it was not an unconditional surrender.
They agreed to unconditional surrender and then got to keep the Emperor. Which makes one wonder if the US had actually offered surrender terms that included keeping the Emperor maybe Japan would have surrendered. Instead they just demanded unconditional surrender.
As with almost everything there are countless reasons why Japan didn't surrender earlier. [1] By June of 1945 Japan's leaders did want out of the war, but were still hoping for a surrender that allowed them to keep much of their holdings (I think people often forget how much of East Asia Japan had solidly controlled for almost 10 years at this point). And they were being strung along by the Soviet union who was supposed to mediate peace, yet had their own motives to prolong the war until they could join.
And even after dropping 2 nukes, and believing the US had 100 more, it took days more, and some additional attacks, to convince Japan to surrender. And even after all this, there was a serious attempted coup.
The official Postdam Declaration (allied surrender terms) didn't mention imperial sovereignty one way or the other, but it appears the Emperor considered it to have been agreed upon prior to the "unconditional" surrender
Some more color, from Wikipedia:
"The Japanese cabinet considered the Allied response, and Suzuki argued that they must reject it and insist on an explicit guarantee for the imperial system. Anami returned to his position that there be no occupation of Japan. Afterward, Tōgō told Suzuki that there was no hope of getting better terms, and Kido conveyed the Emperor's will that Japan surrender. [...]
That day, Hirohito informed the imperial family of his decision to surrender. One of his uncles, Prince Asaka, then asked whether the war would be continued if the kokutai (imperial sovereignty) could not be preserved. The Emperor simply replied "of course.""
Hiroshima was a supply and logistics base for the Japanese military with 40,000 soldiers in the city roughly 1/2 where killed by the atomic bomb where closer to 1/4 of the civilian population was killed. It also supported a large war industry, manufacturing parts for planes and boats, for bombs, rifles, and handguns.
By WWII’s low standards that was very much a military target. In comparison Japan tried using unguided balloons to bomb the US which while completely ineffective targeted everyone. https://en.wikipedia.org/wiki/Fu-Go_balloon_bomb
