After WW2 General MacArthur was appointed the Supreme Commander for the Allied Power (SCAP), which basically put him in charge of the allied occupation of Japan, which would ultimately have a huge impact on the shape of postwar Japan.
Assuming that politics, death, or other butterflies prevents Doug from being appointed to such a high office, who else would have likely been appointed, and is there anything that they might have done differently. For example MacArthur was opposed to Hirohito abdicating, and granted immunity to members of the royal family during the war crime trials, so it's not hard to imagine a different SCAP supporting abdication and a regency. Would there have been someone willing to push for Japan becoming a republic?