J-Rock

[Kikumaru]

Hmmm..I don't have too many I listen too, but..here goes:

X Japan

Gackt (his older work)

Miyavi (older work as well)

L'Arc~en~Ciel

Tetsu69

Iceman

Porno Graffiti (some is J-Rock)

Luna Sea

Asian Kung-Fu Generation

Kimeru (He does mainly pop, but I do like his rock songs)

T.M. Revolution (same could be said for Takanori. He mainly does pop, but his rock is good too)

Mad Soldiers

Nightmare

Maximum the Hormone

UVERworld

That's all I can think of at the moment

EDIT: Remembered one more