Most of the areas were never under Allied control at the end of the war so there were no film crews to cover what had happened. And unless it is on film some people have trouble picturing it. The best place to find the records is, oddly enough, in Japan. They do not go out of their way to make them known but the records are there. And what they reveal in their dispassionate way is enough to give you unending nightmares.
Oh trust me, I know what the Imperial Japanese Army did in WW2 and in China. Always have. When I was a kid in school other kids were in the play ground and I was in the library devouring everything I could about the Second World War. I was fascinated by this cataclysmic, world-altering event.