both before the war began (China, Korea) and after the US entered the war (POW camps, Philippines, other occupied territories).

Literally everything that happened to Japan in WWII was the consequence of actions taken by Japan, including their national unwillingness to surrender when it was obvious after 1943 that the war was completely unwinnable.

Certainly the average Japanese probably had nothing to do with the events that led the country to the state you described, but actions have consequences and unfortunately in that particular case the actions were initiated by their government.