From the link: "" The aggregate strength of the Homeland armies would...total 2,903,000 men, 292,000 horses, and 27,500 motor vehicles...." Also, I have read printed literature on the matter that put Japan's homeland defense reserve number of fighter planes in the thousands
"Your reference discusses "domestic upheaval" and eroding "morale" in Japan. "
Again, from the link.:
""The fundamental political reality is that it was Japanese, not American, leaders who controlled when and how the Pacific war would end. Those insisting that Japan's surrender could have been procured without recourse to atomic bombs cannot point to any credible supporting evidence from the eight men who effectively controlled Japan's destiny: the six members of the Supreme Council for the Direction of the War, Lord Keeper of the Privy Seal Kido, and the Emperor. Not only has no relevant document been recovered from the wartime period, but none of them, even as they faced potential death sentences in war-crimes trials, testified that Japan would have surrendered earlier upon an offer of modified terms, coupled to Soviet intervention or some other combination of events, excluding the use of atomic bombs. "
Exiting the war with "honor" was paramount to the Japanese and they were willing to die for that cause alone. Is it better to starve a million people in a blocade over years and years time or kill 100,000 in one blast and force a surrender?