I question the sincerity of “peace feelers” to the USSR. Richard Frank’s “Downfall” is the best source on Japanese actions during this time-—they weren’t looking to surrender but to negotiate terms so they could stay in China. Potsdam was already done and the Russkies promised to join the war “as soon as possible.”
That’s my understanding as well. Given that the Japanese military quashed any peace overtures, just how peace was supposed to be implemented seems impossible. Of course, I’m no Howard Zinn.