I had actually heard a theory about how the Japanese Military changed after WWI. The rapid expansion caused a large influx of people who were more prone to brutality than the average Japanese soldier.
When I said I have called them JAPS, I was not impling that I don’t like them. I like them fine. It’s their boring cars I and some of my friend’s don’t like, so we call them rice-grinders or Jap cars or something like that.