The Japanese considered anyone not Japanese as inferior ( they still do). They also regarded surrendering as disgraceful and scorned Allied troops who surrendered as cowards who didn't deserve normal enemy prisoner treatment. By contrast, the Nazis treated pows fairly well with the exception of the Russians who they were pretty awful to. Japan's atrocities in China towards the civilian population rival anything the Nazis did, but they did not limit their atrocities to the Chinese. They slaughtered over 100k Filipinos in Manila when retreating after we invaded in 1944 with the return of MacArthur.
So keep that in mind the next time the leftists start whining about Hiroshima and Nagasaki. The A-bomb saved about 100k American lives who would have died in an invasion of the home islands... and also about a million Japanese civilian lives who would have been sacrificed to try to stop us.