J-rock is what I listen to mostly, never really had a taste for J-pop:
*Dir en Grey
*Malice Mizer
*Luna Sea
*X-Japan
*L'arc~en~ciel (but they're bordering on pop)
*Due' Le Quartz
*Kagrra
*MUCC
are the standards
My personal favourites are:
*Plastic Tree
*Guniw Tools
*Miyavi
*Schwarz Stein (and both Kaya and Hora's solo projects)
*Maximum the Hormone
*D
Hope that helps some?
i dance where the darker crowds dance/in the pitch black clubs in a clove-stained trance