At no point have I claimed to support the idea that the Soviets deserved the credit for triggering the Japanese surrender. That was the whole point of my posting the link to the Jon Parshall video in the first place (have you even watched it?), which clearly set out the sequence of events based on more recent information from Japanese archives.
What I have sought to do with my posts is set out what actually happened with regard to the Soviet invasions to correct the inaccuracies that you in particular, and others, have posted in this thread. For example your claims of:-
1. no Soviet amphibious capability. As they managed it in Sakhalin & the Kuriles, it was perfectly possible for them to make the short hop to Hokkaido.
2. an "antiquated" Soviet Pacific Fleet, which I've shown it was not
3. a need for carriers, naval aviation, long range strategic bombers just because the western allies had them.
You seem to contradict yourself when writing about a Soviet invasion of Hokkaido.
. "We're talking about a million troops on the scale of Normandy, not a few thousand troops to obtain an outlying island."
"As far as Hokkaido being relatively lightly defended...."
Not sure why you need an amphibious operation capable of transporting a million troops, when the Japanese Fifth Area Army was a relatively weak and ill-trained force by all accounts. And Soviet plans had limited objectives in such an invasion. Even historians can't agree as to whether the Soviets could have pulled it off or not. As it never happened you can choose to believe what you like.
en.wikipedia.org
And as for your statement:-
"The U.S. also had plans in the works to add Shikoku and Hokkaido to its invasions, if they deemed it necessary."
Operation Olympic to invade and occupy the southern half only of Kyushu only starting 1 Nov 1945 were well advanced. The object of that operation was to gain real estate for airfields to support the next phase. That was Operation Coronet scheduled for 1 March 1946. Planning for that was much less well advanced and didn't extend beyond the first 3 months of such a campaign in the area of the Kanto Plain.
If Japan had still not surrendered then it was recognised that further action might be required. But no planning beyond a vague outline had been carried out AFAICT
"While U.S. planners hoped that the Japanese would surrender after Coronet (or better still, after Olympic), they did not discount the possibility that the enemy might still hold significant reserves elsewhere in Japan and refuse to capitulate. In case of such a contingency, the committee drafted a plan, JWPC 333/1, which called for assaults against remaining Japanese pockets in the Home Islands in order to destroy major enemy forces and secure key areas.
25 The plan listed five potential targets: the Shimonoseki Strait area of Kyushu, the Osaka-Kobe-Kyoto area of central Honshu, the Nagoya area of Honshu, the Hakodate-Aomori-Ominato area of Honshu and Hokkaido, and the Sapporo Plain of Hokkaido. The committee estimated that the Osaka-Kobe-Kyoto, Nagoya, and Hakodate- Aomori-Ominato operations each would require eight divisions, Shimonoseki Strait nine, and the Sapporo Plain five. If possible, these operations would employ troops already in the Western Pacific in order to simplify logistics and avoid the use of the strategic reserve based in the United States. The first attack was tentatively scheduled for 1 July 1946, with the target dependent upon the strategic situation.
26"
Note that while those additional outline plans envisaged the possibility of additional invasions on Kyushu, Honshu or Hokkaido, they did not include Shikoku. That wasn't the first time Shikoku had been rejected as a possible target for invasion.
muskeg13 advised here tries to proof that the Japanese were so scared about the bomb that they were forced to end the war there and then, saving thousands of lives in the process. The one I advised here has a different take. It notes that the council meeting about the surrender took place as late a s 3 days after the bomb as council members had "more important things to do first". This indicates that they were not much fazed by the mass killing of their own innocent citizens. This is hardly surprising giving the generous way the Japanese leaders had spend the lives of their own people during the previous years. They were more concerned about keeping the Japanese traditions than keeping people alive. The discussions therefore were not mostly about the atomic bomb, but about the Russian invasion in Manchuria. They decided it was better to surrender to the Americans as they thought, compared to the Russians, the US would be more inclined to leave the traditions and especially the Emperor alone (history proved that right). 
