We all have our cultural idiosyncrasies, but in regard to the much written Japanese feelings towards blacks, I believe that there is a direct correlation to their feelings and the media, particularly newspapers, radio and television here in America.
When blacks are depicted in the newspapers, for the most part it's crime related. In commercials on television, we can't just be regular consumers, we have to wear ridiculous clothes, moonwalk or do some strange facial or body gesticulation.
The media shapes many a mind and not always in the right form. People coming to America seem to have preconceived ideas about our attitudes, about Americans in general, i.e., who has the power and who doesn't. (Blacks don't.) They seem to be saying, "when in Rome" etc.
This thinking is not just Japanese, unfortunately.