Esplain? I could take that one a few different ways.
The Japnese were firmly convinced that non-Japanese were less than human, and deserved no mercy. The horrors they visited on Allied POWs and on Chinese civilians in Nanking were enough to make the Nazis vomit.
The Americans were also encouraged to view the Japanese as less than human, through wartime propaganda that depicted them variously as monkeys, rats, or vampires. The U.S. interned native-born, loyal citizens of Japanese ancestry.
Now, let's get clear that America's acts of racism were not in the same ball park with the Japanese. They weren't in the same league. They weren't on the same planet. So when I say that it was a racist war on both sides, I'm talking about rudeness on one side and atrocity on the other.