J-Rock (lol, a lot of this stuff I haven't listened to in a while, but I still like it) -
Alice Nine
Aliene Ma’riage
Asian Kung-Fu Generation
Atsushi Sakurai
Aushvitz
Aya
Baroque
Buck-Tick
Chirolyn
Clothoid + Doll
D
Deadman
Deathgaze
Deflina Ma’riage
Dir en grey
FLOW
Gackt
Gazette
Girugamesh
Gullet
Guniw Tools
hide
hide with Spread Beaver
Hyde
Inugami Circus Dan
Janna Da Arc
Kagerou
Kaggra,
Karimero
Kozi
Kra
L’~Arc~en~Ciel
Lucy
Luna Sea
lynch.
Malice Mizer
Merry
Miyavi
MUCC
Nightmare
Onmyoza
Panic CH*
Penicillin
Phantasmagoria
The Pillows
Plastic Tree
Polysics
Psycho le Cemu
Raphael
Rentrer en Soi
Rice
Schwein
Shiina Ringo
Thee Michelle Gun Elephant
Tokyo Jihen
UnsraW
Vidoll
Vinett
Yoshiki
J-Metal:
Blood Stain Child - Pretty good Melodic Death Metal band that started off sounding similar to Children of Bodom, but lately their sound has gravitated towards In Flames with techno elements.
http://www.youtube.com/watch?v=HStZyp93LDAD'espairsRay - Pretty good Industrial Metal band
http://www.youtube.com/watch?v=GDVAe60ypAkGalneryus - Pretty awesome Power Metal band
http://www.youtube.com/watch?v=zjnNOkjnLVIHizaki Grace Project - Neo-Classical Metal band
http://www.youtube.com/watch?v=rDjumx-mY-YMoi Dix Mois - Gothic Metal, though I thought Mana's work with Malice Mizer was a bit better.
http://www.youtube.com/watch?v=UBOldHfxb4ISex Machineguns - fu-king LOVE these guys. Awesome Speed Metal; much props to these guys for keepin' the genre alive and fresh.
http://www.youtube.com/watch?v=LnXUBEJKJtESigh - Pretty awesome Avant-garde Black Metal band
http://www.youtube.com/watch?v=tBhQY-KgwfsVersailles - Neo-Classical Metal band. Hizaki from Hizaki Grace Project is the guitarist.
http://www.youtube.com/watch?v=htUKM1pltlg...feature=relatedX-Japan - fu-king awesome how they got back together, though I miss hide.
http://www.youtube.com/watch?v=WzHbHxSEtVQ