Gaijin
If you are a Westerner (and particularly if you are Caucasian) you should be aware that you are a 'gaikokujin' or 'gaijin'--a foreigner. Of course, everyone who is not Japanese is a 'gaijin', but the ones of us who stand out are most readily placed in this category. Some Japanese boys are self-proclaimed gaisen, which is the Japanese equivalent of 'potato queen'--Asian boys who like Westerners. On the other hand, some Japanese have absolutely no interest in foreigners, so you may be snubbed for that very reason. One possible explanation for this love/hate relationship may stem from the fact that foreigners are rumoured to be very well-endowed. Hmmm. Let it be said here that while many Japanese boys proclaim to be 'small', this is certainly NOT always the case (just so you know).
You should not let this potential bias deter you. There are lots of kind Japanese men who, even if they are not gaisen, are pleased to chat with a foreigner. Take a chance, take your time, and have fun!