In reading through this whole thread to get up to speed, I have seen some truly corny toejam spewed out here.
First of all, the Japanese were not contemplating surrender as a whole. Emperor Hirohito was thinking about some kind of negotiated settlement. But the Military tribunal in Japan wanted to fight to the last. Inside the Tribunal were officers' who were willing to pull off a coup, and overthrow Hirohito and keep fighting, even after the A-bombs' were dropped. However, the coup was foiled.
There was no secret made of Japanese atrocities during WWII. Junior officers' would practice Samurai Bushido swordsmanship skills' on american POW's by beheading them. They tested Biological weapons' on Chinese prisoners. The Death March of Bataan should not need a description. There are more instances' beyond these I've given here; I'm not gonna take the time to put them all down here. Suffice it to say, that on Moral grounds, by the end of the war, The Japanese did'nt have a leg to stand on.
Now, the necessity of dropping the weapons, and the overall justification, leave out a few other points' that turned out to have a big impact on our post-war world, as well. For instance, The Soviet Unions' declaration of a war against Japan, Only 2 weeks' before the end of the war, Probably did as much to hasten the use of Atomic weapons' as anything else. IMHO, Truman now faced the real danger, of the Soviet's invading and grabbing half of Japan whilst America took the highest casualties of the war trying to implement Operation "Downfall". The Japanese plans' all centered around an American invasion; It did not take a Soviet incursion into account. However, by dropping the Atomic Bombs, and forcing Japan to Surrender to the U.S. as it was then, It enabled the U.S. to occupy and reconstruct Japan as what it wished it to be- A Pro-Western Democracy, Rather than something like what politicians' had already seen in the split up of Post-war Germany, and the Eastern European States' such as Czechloslovakia, Poland, Yugoslavia, Romania, et al, a Communist Puppet-satellite state.
My last point would be, that with the invention of the Nuclear Weapon, it was actually fortunate that it was actually used, and shown to be the terrible, world changing weapon it was. Everyone in the world, from the Highest Politicians' to the common citizen, knew what they were, and what they could do. If the weapon had been developed by some power who kept it secret, and stockpiled them through peacetime, never using any of them until it wanted to make the same kind of Hitlerite gamble to take over the world, we might not have been able to have this conversation right now. Leaders' who had never seen pictures of the devestation of Hiroshima or Nagasaki, naive to the powers' they controlled, might have been too reckless in their political dealings' in a world which had atomic stockpiles, but knew not the implications' of their actions. Once invented, they can not be un-invented. Once used, they can not be ignored, either.
There will most likely always be Japanese who are embittered by the A-bombings. Maybe even a good percentage of the country. Just the same as quite a few americans' of the Greatest Generation would refuse to buy anything made in Japan. Who would not be caught dead driving a Japanese made car, if they could possibly help it. It is fatalistic, at best, to try to do anything other than to tell history for what it was. Which was an Imperialistic Japan's bloody attempt to take over the Pacific Rim and a large part of mainland asia, crushing everything under it's heel in the process, using any means' it so desired, no matter how barbaric and cruel. Once they crossed that line, they should have realized that setting the tone of the fight in that matter might cause reciprocations' in kind...or with interest, many times' over. In other words, don't march prisoners' to death, not feeding them, bayonneting those that drop from exhaustion, and then expect everyone to just say "Ok, I know your doing this to American soldiers' who should have been treated according to the Geneva convention, It's ok, I won't put my entire country into the single goal of kicking your head through your ass, permanately, at the earliest oppurtunity."
If the Japanese wish to fool their future generations' into thinking that what happened to them at Hiroshima and Nagasaki was unjust, and that it should be attoned for, fine.
We'll just have to use more Megatonnage on them next time, to make the lesson stick.