The Korean War was a big part of that. The U.S. needed to industrialize Japan fast.

I think the best thing to ever result from the Cold War was the lack of war between major industrialized nations, which had a lot to do with a much more fair system of international trade than before.

Note that Japanese war criminals as a whole got off much easier than their German counterparts.

Yes, that is unfortunately true. And there were some very serious war crimes that didn't result in a trial and a conviction at all.