The US stance of "unconditional surrender" and what its "varying" - they changed - parameters meant to the status of the Emperor were in question.
So, the Japanese continued to fight on; it was only when the Emperor ordered an end of the fighting that the killing stopped.
There was just one more atomic bomb (in transient to Tinian) available ... they were "hand made" at the time. Had the Emperor not ordered the end ... unconditional surrender was not an option in the Japanese mind-set ... no matter how many atomic bombs were dropped.
The **** the Japanese would have been looking at in another six or seven weeks would have been considerably worse than more atomic bombs. That would have included 100 US carriers with no further invasion protection duties, i.e. nearly immune to kamikaze attacks, Midway carriers with armored flight decks and compliments of tigercats and bearcats on board, LeMay resupplied with incindiaries which he’d run out of in July of 45 and operating from Okinawa 350 miles away instead of the Marianas 1400 miles away, i.e. as if the number of B29s had been tripled, and about 20,000,000 people who used to live in cities walking around in the forests, and their entire merchant marine on the bottom of the ocean.