Hiroshima 70 years ago

[Anomalocaris]

In the prevailing conditions in Japan in 1945, when most military installation accessible to pin point strike from off shore has already been destroyed, yet japan's will to resist appear to be unbroken and Japan's ability to resist still appeared considerable, it was not possible to not hit japan in ways that would hurt, and it was not possible to hit japan in any way that would hurt that does not involve hitting mostly civilians.

If the U.S. had actually cared whether thousands of Japanese civilians died or not, they could have told the Japanese that the U.S. had such a bomb and suggested demonstrating that it worked, without blowing up cities.  But the simple fact is, the U.S. did not care about the Japanese people, and were totally okay with using them in a demonstration.  That is why "virgin" targets were selected.  And they were "virgin" targets because actual military targets within range had already been attacked.

You forget Both the actual, and the anticipated effect, both in property destruction and casualties, of the atom bomb pales next to those of any one of several previous fire bombings attacks the U.S. army Air Force had already conducted against major cities in Japan since early 1945, including Tokyo.  

Keep in mind the atom bomb raid on either Hiroshima or Nagasaki were far from the most destructive or the most deadly air raids conducted against Japan or Germany.

Clearly the U.S. already demonstrated repeatedly it had workable and repeatable means to inflict damage and casualties in each raid that goes far beyond what a single atomic bomb could do.   

Japan had not been able to thwart any of those raids.

The U.S. had on many occasions dropped leaflets giving advanced warning of these impending raids, sometimes 2 weeks in advance.

The Japanese had not heeded the warnings and evacuated those cities, and had instead chosen to absorbe the upcoming damage and casaulties in each of these raids, which were in many cases greater than any a single atom bomb can hope to inflict.

Japan had not surrendered.

So why would any mere demonstration of another means of inflicting an what is by 1945 frankly already an Un-extraordinary amount of devastation be rationally expected to impress the Japanese more than actual and repeated application of even greater destructive power that had happened before?

I am not arguing the U.S. cared about the japanese cvilians.   On the whole It didn't.   But if it did, it is still likely it would have done this because in the circumstances it was prudent, not clearly a worse alternative than something else which it would have had to do in its stead, and served a geopolitical need independent from any humanitarianism.