Odds are not only would we have had to fight in Japan to overthrow Tojo, we would also have wound up fighting in Japan afterwards to stop the Reds from taking the entire country.
Had we invaded Japan, the fighting would, literally, have been house-to-house as predicted. The Japanese soldiers were smart, clever and willing to die for their emperor.
I don’t doubt that we might have ended up fighting Stalin for the parts of Japan that they might have ended up controlling. In Germany, that’s what the Berlin Airlift was about.
Things were delicate, to say the least, for many years after Japan’s surrender.