Hiroshima was an excellent place to demonstrate the atomic bomb.
The USA tested the Trinity Bomb July 16, 1945. The Japanese tested their own atomic bomb in late February 1945 in Hungnam, Korea, about 4-1/2 months before us. Their bomb was about 1/10th the size of ours and they used up all their atomic fuel in the one test with nothing to spare.
If they’d been able to get more uranium they would have destroyed an American city with it.
To aid in the Japanese effort, Germany shipped 560 kg (1,230 lb) of unprocessed uranium oxide to Japan in April 1945 aboard the submarine U-234, which surrendered to an American destroyer soon after the German defeat and so Japan never received the uranium.
What a pity. They were so close./sarc