Sex Machineguns - Think Judas Priest and Iron Maiden but faster. Speed Metal, with some songs bordering on Thrash Metal. Probably my fav. Japanese Metal band.

Their music videos are always weird and funny too.
Sex Machineguns - Ai Koso Subete
http://www.youtube.com/watch?v=TXbkpAR6z-gSex Machineguns - Burn
http://www.youtube.com/watch?v=menE5G7z_14Sex Machineguns - Aijin 28
http://www.youtube.com/watch?v=L-ZzzwARpwwSex Machineguns - Mikan no Uta (live)
http://www.youtube.com/watch?v=LnXUBEJKJtESex Machineguns - Sakurajima (live)
http://www.youtube.com/watch?v=mKEOW27_WssX-Japan - The most famous of them all.
X-Japan - Silent Jealousy
http://www.youtube.com/watch?v=WzHbHxSEtVQX-Japan - Dahlia
http://www.youtube.com/watch?v=kJsxgQyN9RkX-Japan - Kurenai (Live)
http://www.youtube.com/watch?v=CgDdpATtGlMSigh - Awesome Avant-garde/Black Metal band.
Sigh- Introitus/Kyrie
http://www.youtube.com/watch?v=tBhQY-KgwfsSigh - Inked In Blood
http://www.youtube.com/watch?v=nsjQ3Suof3khSigh - Death With Dishonor
http://www.youtube.com/watch?v=C5o3JBkakgoBlood Stain Child - Melodic Death Metal band that sounds a lot like Children of Bodom and Norther with a bit of techno thrown in.
Blood Stain Child - Clone Life
http://www.youtube.com/watch?v=b7EkveEZbmQBlood Stain Child - The Road to Ruin
http://www.youtube.com/watch?v=HStZyp93LDABlood Stain Child - Truth
http://www.youtube.com/watch?v=-gVvKI3ptCEBlood Stain Child - Freedom (actually, starting with this album, they switched gears and started sounding a lot more like In Flames with techno instead...

)
http://www.youtube.com/watch?v=2oi-8xl7uZ Galneryus - Pretty awesome Power Metal band
Galneryus - New Legend
http://www.youtube.com/watch?v=zjnNOkjnLVIGalneryus - Struggle For the Freedom Flag
http://www.youtube.com/watch?v=1I_oi68vxZkGalneryus - Silent Revelation
http://www.youtube.com/watch?v=rfBI_kmDlNQGalneryus - Everlasting
http://www.youtube.com/watch?v=KzAfatAMOQ4Moi Dix Mois - Gothic Metal. Spiritual successor to VK/Goth rock band Malice Mizer.
Moi Dix Mois - Dialogue Symphonie
http://www.youtube.com/watch?v=UBOldHfxb4IThat's about all I got for ya.