Race certainly had something to do with it. Just look at political cartoons of the era and mutilation of Japanese soldiers’ corpses, the collection of gold teeth and skulls as souvenirs. Far more ethnic Japanese living in America were interned than ethnic Germans or Italians. But I think it was also the way they fought and their Bushido culture at the time. Their military had no respect for human lives whether it was their enemy, civilians, or their own soldiers. They fought dirty, used suicide tactics, tortured prisoners, devastated civilian populations wherever they went. Hence why I mentioned the Okinawa civilians, the Japanese soldiers used them as human shields. The Germans were culturally and racially much like most of America.
A good read is “The Ultimate Battle” by Bill Sloan, it sheds a lot of light on the culture shock American soldiers and Marines received from fighting the ever-desperate Japanese during the worst battle of the Pacific campaign.
Anyway, I went way off the rails here lol
My grandfather used to say that the Japanese were building cheap, fast motorcycles to kill young American men as revenge. I think he was joking though.