The vast majority of Japanese aren't racist. They just have xenophobic tendencies stemming from the fact that some 93% of the population is ethnic Japanese and they simply don't know anything about foreigners. In larger cities you will probably be ignored for the most part (except of course at restaurants/cafes where attention makes sense), since more people in cities are used to seeing foreigners. In smaller towns -- especially those that don't get tourists often -- you can expect to become sort of a spectacle. Whether that's good or bad depends on your perspective, but most of the time it's for the better. People will generally be friendly, offer to help (if you aren't too intimidating), etc.
Japanese don't tend to differentiate caucasian ethnicities. If you're white, you're white; they don't see much difference between Europeans, Americans, Canadians, Australians, etc. Unless you're from America or Australia, I doubt too many Japanese could even find your home country on a map. On the other hand, if you're non-Japanese Asian (Chinese, Indian, Filipino, etc), you might experience some negative attention -- particularly if you can't speak the language. But much of that stems from associated illegal immigration, some stereotyping of crime, and so on.
