The Soviet Pacific Fleet had ships in Vladivostok that they were readying for an August 24 invasion of Hokkaido after successfully moving troops to take Sakhalin and Northern Korea. https://foreignpolicy.com/2015/08/05/stalin_japan_hiroshima_...

If Japan was not caught napping, I believe 100% that this operation would fail. If 100s of suicide attacks those ships would sink with troupes and all. Even if they land, an land invasion supported by sea based logistic is incredibly difficult.

And the troupes in Japan were not at all like the army left on the continent.

Japan was caught napping. They were preparing for an allied invasion from the South. The troops in Japan had been cut off from supply of raw materials from the continent.