Recommendations? Hmm...right now I'm listening to a lot of stuff that isn't really pop, but it's not really rock, either. I think Olivia Lufkin and Porno Graffitti (both of which I highly recommend) are more like crazy Japanese theme parties on crack. The former has everything from pop tracks to ethereal soft-rock to "let's scream a lot" music. The latter has everything from salsa-beat Jpop to stuff that would fit in at a disco to stuff that sounds like it's straight out of the 1960s American pop scene to stuff that is fairly rock-ish. Go figure; they're all bizarre. Whatever Haruichi is smoking when he writes his songs, I want some -_-;;
If you're looking for quality vocals, Kokia sings amazingly, as does Sakamoto Maaya. If you like girl-bands, I like Do As Infinity, Day After Tomorrow, and Every Little Thing. BoA and Hamasaki Ayumi aren't bad...but I really have to be in the right mood to listen to them. I'm not a huge fan of jrock, as most of the male vocalists tend to sound like they're swallowing an angry cat while singing, but L'arc en Ciel is okay sometimes.
Yeah, I could make a lot more recommendations, but I'd have to know more what you like to listen to. *^_^* And Soulseek is a really good place to get Asian music - there are chat rooms for just about every genre, as well, so you can get really specific recommendations from people who particularly like Asian punk, for example, vs. people who just stick with pop. ^_^