As in backchannels of primarily just Shigenori Togo. The Japanese war council was unanimous in rejecting unconditional surrender, and bitterly divided on the terms willing to be offered for conditional surrender. The idea that it was the safety of the emperor they were stuck on is new to me. Perhaps you are referring to Togo's statement that the Potsdam declaration would be accepted provided the position of the Emperor was maintained? Firstly, this was not an official Japanese government offer, secondly it's not exactly as if it's a reasonable request to allow a defeated belligerent to maintain their existing government.
Togo reasoned
that "the introduction of a new weapon, which had
drastically altered the whole military situation, offered the military
ample grounds for ending the war." He proposed that surrender
be considered at once on the basis of terms presented
in the Potsdam Declaration. (When those in the peace party
talked about "accepting the Potsdam terms," they meant acceptance
with one crucial condition: retention of the emperor
system.) However, the military authorities refused to concede
that the United States had used an atomic weapon. Given the
army's intransigence, it was impossible for the cabinet to take
up Togo's proposal.
So, if it's established that the Japanese government was store concerned with its own political positioning that winning the war or defending the people of the country, and an appropriate response is to immediately bomb a quarter million civilians without any ramp up or targeting of military or government targets?
The morality of the action of dropping 2 nuclear bombs on Japan is separate from the question of whether the Japanese government was making a bona fide attempt to surrender.
Edit: Sources From The Shock of the Atomic Bomb and Japan's Decision to Surrender: A Reconsideration http://www.mconway.net/page1/page15/files/Shock%20of%20Atomi...