In our timeline after WWII Germany was given harsh treatment and they had to assist in the rebuilding of their towns and of digging graves fro the killed Jews from the Holocaust.
While Japan was punished they got off far lighter than Germany was and have dedicated museums to their veterans and don't mention the atrocities they committed in school much to their neighbours annoyance. In Germany it's compulsory to learn about the evils of the Holocaust and Nazism.
So what if Japan was treated more harshly i.e forced to rebuild S.Korea and obey demands such as renaming the Sea of Japan, apologising and giving repartitions for the war crimes to China, Philippines, Indonesia and the Korea's and giving S.Korea multiple lands that are disputed?