I mostly used Franks Downfall for the quotes in Surrender of Japanits the best single reference I know  The emperor made his decision on the night of August  Nevertheless the time has come to bear the unbearable I swallow my tears and give my sanction to the proposal to accept the Allied proclamation on the basis outlined by the Foreign Minister That being the onecondition position which the cabinet then accepted But the Allies didnt so there followed a couple of days of telegrams back and forth The surrender wasnt a done deal until August  when the Japanese gave up on an explicit guarantee for the Emperor I have listened carefully to each of the arguments presented in opposition to the view that Japan should accept the Allied reply as it stands and without further clarification or modification but my own thoughts have not undergone any change  I linked to it before but heres an interesting firsthand account