Its not terribly popular where i am, but i go to an art school and everyone there is really into anime (its kind of ridiculous....they run around weariong Naruto headbands as an everyday accessory....we call them Narutards.) When it comes to J-music though, the people there are more into Jrock than Jpop. I'm one of the few Jpop fans there XD (the most Jpop people get there are the ones that watch Pokemon all day and listen to Mini moni *HATES MINI MONI*)
BUt yeah, theres this place called Mitsuwa Market place that they all go to and they have a big area thats all jpop and jrock CDs, magazines, you name it and its ALL authentic
Made in Japan, Avex trax labels and all XD It's wonderful. But pricey....BUT WONDERFUL XD