[waterballoon]

Well, I think it's pretty subjective.

I wouldn't expect someone who says, "I'm a fan of Japanese music/J-Pop!" to know the "mainstream" artistes, cos J-Pop can mean A LOT of different singers/music, and not just the one we know.

Granted, if someone was a huge fan of older J-Pop music and asked if you knew Seiko Matsuda/other older singer, you might not know who they are either if you're not into oldies. Similary, if a J-Pop fan is crazy about Enka, and you're not into Enka which means you do not know any of the artistes in Enka, does that make you less of a J-Pop fan?