I am a total fan of traditional Japanese music, and just two modern composers cut the mustard for me: Kenji Kawai and Yoko Kanno.

Most J-Pop is rather annoying for me, since I'm not comfortable with over cheery sugary tunes, but some of their most commercial metal (which is what I've gotten to hear - to be honest, haven't looked to deep into it) like Dir En Grey or Galnyerus has proven to be interesting, to say the least.

On the electronic scene (which I tend to think is a different beast on it's own given the variety of sub-genres), Japan totally stomps Western DJs. DJ Sharpnel, DJ Technorch, M1dy, TJ MS-DOM, DJ SoH or RedOgre, just to name some of the most popular, are constantly an innovative force, capable of breaking most of common trance's barriers. I used to listen to Tiesto, Safri Duo, and the like, but since I started with DJ Sharpnel, I've never looked back.