Everything I've seen and read indicates the Japanese had offered a number of times to surrender with barely any conditions: the only main one being that the Emperor remain in power and not be pressed for war crimes, etc.

Given that the Emperor of the time was very anti-war and doing everything to convince the military to give up, I can't help thinking the Yanks deliberately refused a pretty fair surrender offer just so they could "blow up some Nips" with their expensive new toy.