Maybe the U.S. tweaks the terms of surrender. For example, making an informal agreement not to execute the Emperor, which we didn't do anyway.
Yes, we avoid bombing the cities of Hiroshima and Nagasaki.
In my mind, here's the challenge: The occupation of Japan already went extremely well. Think pretty far out on the bell curve. So, how can you have a major change and still achieve this level of success or more? Find me a way.