There is no evidence that the Japanese were planning on surrendering. The Allies' options were basically a choice between launching Downfall, hoping the nukes would force a Japanese surrender, and letting the Japanese Empire stay in power (and the last one wasn't going to happen).
Quite the opposite, in fact, considering that with even the hardliners acknowledging that Japan was beyond any hope of victory, it still took an ultimatum, ample warning of the planned bombing, and not one, but two, nuke strikes before they actually surrendered, and this decision was still met with an attempted coup from the hardliners.
If you insist otherwise, please show evidence of the assertion that the Japanese were actually planning on unconditionally surrendering and wouldn't have tried for what we have historical citation they were hoping for, i.e. a favourable negotiated treaty with the Allies with minimal Japanese concessions and the Emperor and military government remaining in power.





