I think there's nuance here that gets lost in the retelling. From what I learned of it in a university course dedicated to many aspects of the topic of that bomb, there was a demand of /unconditional/ surrender but Japan wanted to keep their emperor. The emperor was really more of a cultural and spiritual persona than a political one, but regardless the US gov't. insisted on an unconditional surrender, including dethroning the emperor. I think there was an offer of surrender by the Japanese if they could keep their emperor. I don't have proof handy and I'm not inclined to dive down that particular rabbit hole right now so I hope someone can support or correct this.