Some of these are in 2009, but I dont think you care.

1. Capsule – Player. This cd is brilliant. experimental techno, floaty voice, heavy beats, turn it up.
http://www.youtube.com/watch?v=6OGG1JQDY1g fast
http://www.youtube.com/watch?v=S57HJGp7mOo slow
2. Radwimps – Altcolony If weezer crossed up with rage against the machine and learned japanese, you’d have some radwimps. They deserve to be world-known I feel.
http://www.youtube.com/watch?v=smH_qPRe3XM

3. Namie Amuro – Past Future. Namie is self described queen of hip-pop, but she has good range into techno and ballads.
http://www.youtube.com/watch?v=gG4aRjRBBb8
4. YUI – Holidays in the Sun . YUI is an extremely talented singer songwriter who has a pleasant voice and emotional authenticity. Can also belt out a rockin tune too.
http://www.youtube.com/watch?v=CHaYO2PIjSU
5. Kana Nishino – To Love . Kana is a pleasant pop singer who is very talented and I feel would be recieved highly around the world. I guess the closest thing is a leona lewis.
http://www.jpopasia.com/play/28475/kana-nishino/aitakute-aitakute.html
6. HalCali – Tokyo Groove . This duo of singer-rappers is full of cheer and goofy dances. I think they are a great model for women because they dress creatively but not slutty at all. Much respect and legit rap skills,
http://www.youtube.com/watch?v=aD_0Nf2nKXg
7. One OK Rock – Niche Syndrome – These guys are the closest sounding to american rock. Quite good and energetic.
http://www.youtube.com/watch?v=Y_tUf_-Xz44
8. STRAIGHTENER – Nexus – I attached their ballad, but these guys have solid energy and sound japanese in a good way. Great guitars.
http://www.youtube.com/watch?v=ADAaN3KNiRk
9. Perfume – Fushizen Na Girl – Like Namie Amuro, perfume is HUGE with insane amount of sales, also they have been around for a long time and debuted at age 13 or something absurd? This is the baseline of ‘pop’ over there, which I like since there is good solid electro groove without that american side-effect of making me want to stab my ears.
http://www.youtube.com/watch?v=y13poaezWDI
10. Michi – All about the girls – A pretty cool half-british girl has a nice voice and varies between pop and rock that reminds me more of the 90s.
http://www.jpopasia.com/play/28869/michi/wonder-woman-ft-the-telephones.html – rock
http://www.jpopasia.com/play/28329/michi/together-again.html – ballad

Also,
immi – spiral – Pleasant vocal electronica. One of my favorite genres but not always the best selling. Got an 80s vibe.
http://www.youtube.com/watch?v=bTjuR9MzD3o
SCANDAL – Temptation Box – I dont think anyone _looks_ more like japan than these girls in punker school uniforms doing coordinated dance moves. The first lyric of this song “SCANDAL will send anything flying”
http://www.youtube.com/watch?v=h52HDb8pU0k
Stereopony – Over the border – Girl-rock is a weird genre I think and hard to find solid music from. I am not sure where the skill lies here, but they have some catchy tunes. It might be part of an “anime” subgenre of jpop, i am not sure what that means.
http://www.youtube.com/watch?v=LxIZuaYmOuc

morepop: mai kuraki, meisa kuroki, saori@destiny, ayaki ikio, ayumi hamasaki, aya kimiki
morerock: tomoyasu hotei, l’arc en ciel, the gazettE