Here's a page on what the author calls Japanese "fringe groups": biker gangs, right-wing parties, otaku, anti-Giants fanatics, and so on. The section on ganguro is kind of dated, but the other bits are interesting. Apparently the Yomiuri Giants are as enthusiastically hated by the rest of Japan as the Yankees are by that section of the American baseball-watching public that isn't New York City. I had no idea that the membership of Japan's "right wing parties" was so small. I guess you would compare them more with American militias than your typical political party, third-party or otherwise.
Via Krakow, a webcomic I follow occasionally.