Heh, welcome to the club. I've been studying japanese for two years now and
most of the music I listen too is japanese. Here are some bands you might want
to try:

Miyavi: Singer/Songwriter who started out as a guitarist in the band 'Due Le Quartz'.
            He has a very distinct and interesting style of playing (something I've been trying
            to mimic for over a year now) and has interesting lyrics. I suggest you check the
            album 'Galyuu' for his harder and earlier works, or 'dokusou' and 'This Iz the
            Japanese Kabuki Rock' for his newer, more interesting works.

            http://www.youtube.com/watch?v=QV1eBdllZng << awesome

Shiina Ringo/Tokyo Jihen:
            Japanese alternative pop. I can't explain why i think she's the most awesome
            japanese singer ever, but I do.

Her reportoire consists mostly out of pop, but albums like 'Shouso Strip'
and 'Muzai Moratorium' bear a somewhat experimental personality, the former
being a bit more traditional japanese.

She also fronts a band called Tokyo Jihen, a band formed out of musicians
from various bands. I suggest you look up 'Dynamite Out' on youtube or
listen to some songs from the album 'Kyoiku'. The songs 'Ringo no Uta' and
'Gunjyou Hyori' are some good examples.

Gunjyou Hyori
http://www.youtube.com/watch?v=_OJoUgK6aZI

Ringo No Uta
http://www.youtube.com/watch?v=Zg3DmKVWYbQ&feature=related



HIGH and MIGHTY COLOR

I can't really say much about this band. It's a form of metal with a rather
cliche setup, the female singing in clean vocals and the male vocalist doing
screams and stuff. I discovered them while watching the third BLEACH season,
for which they provided the soundtrack (Ichirin no Hana). If you haven't
heard it yet, look it up. Their best album is Gouon Progressive.

Ichirin no Hana
http://www.youtube.com/watch?v=ZTL_lR7KglQ

Yes but in that case you need really clean music where the lyrics are really easy to hear which...isn't at all like the majority of jpop/rock/etc.  He'd be better of with something like recordings of folk music or something, that would probably be the most beneficial to him.

Actually, I've learned that learning Japanese through listening to music
is not as easy as it sounds. It's very hard to pay attention to the lyrics
when you're just listening, especially in Japanese. This way, the sounds
will register, but you'll hardly benefit from it in the long run.
Also, a lot of japanese music is written in poetry form.

I've gotten my hands on Pimsleurs Course Japanese, which has worked
much better for me. It might also help watching Japanese Live action films/
series, but only if you already have a good basic understanding of the language.

Other than that, never try to learn Japanese by watching anime. The sentences
and word combinations used in most anime are in no way suited to base
your Japanese fluency on.

Well usually I wanna sing along so I find a lyric... I learn a little that way

Anyway, my faves are Flow and Nightmare

M-Flo, yes.

M-Flo? Nah, I was talking about this one

I know. M-Flo was my recommendation. :p

It was a half-joke, because I know a lot of people don't like them, but they're the only Japanese artist on my ipod.

World's End Girlfriend & Kashiwa Daisuke for post-rock/contemporary classical/whatever. Both are immensely talented and highly recommended. Think Godspeed You! Black Emperor but more electronic.

Seconding Boris, but Pink & similar albums are not at all what they are best for. Drone or get out.

Chaos Royale for fucked up noise / hip-pop mashups. And Noise/Girl (his older project) for equally fucked up harsh disco.

大野まりな and とろ美 for trve kvte akiba-pop.

this topic is full of faggots, fuck. the octave doctor is pretty much right with what he said.

also, recommending him post-rock shit is useless, he says he wants to use it to learn the language, i don't think world's end girlfriend even HAS lyrics.  i don't even know how you're going to try learning a language through music??? i can barely even understand a lot of english artists now, this sounds like the stupidest way to do it.

also, as far as japanese goes, asobi seksu.

Back-On, if nobody said it already.

I listen to japanese jazz/fusion every now and then, it's mostly pretty ridiculous (they have incredible amounts of embarassing jazz fusion crap)

Hiromi (saw this live a while ago (I HAVE 5 CDS 2 OF WHICH ARE AUTOGRAPHED (FUCK!!!)))
http://www.youtube.com/watch?v=5mK2fv7y9YY
http://www.youtube.com/watch?v=d5WnLSmA35w
http://www.youtube.com/watch?v=PcccRCdOx2Y

Masato Honda (hilariously gay fusion but i looooooove it)
http://www.youtube.com/watch?v=3N6h-DHmyJ0
http://www.youtube.com/watch?v=s0Yxj90AR30
http://www.youtube.com/watch?v=Hj9VexmEqM8 (from T-SQUARE, a band he used to play in)

PE'Z
http://www.youtube.com/watch?v=YDSf8Lo2pU0
http://www.youtube.com/watch?v=ngXcbynPtGo

Then there's Yellow Magic Orchestra, Flower Travellin' Band and Boris which Chef already mentioned. I think this is pretty much all japanese music I've ever really listened to. Japanese music is mostly garbage, but that's probably true with every country