Well the Japanese got to keep their emperor, so “unconditional” doesn’t mean without conditions. Ha ha.
While this is true — it wasn’t really part of any treaties. We basically made backchannel assurances through the Swiss that we wouldn’t go after the emperor.
As much as this was to avoid the blood of Operation Downfall — another reason besides the important one (saving several million lives) was that it allowed us to keep Stalin and the soviets out of Japan.