Ayumi Hamasaki, any songs from her, but the earlier ones have a higher pitch and the recent ones (2006 and up) have a more mature voice . Good thing about Ayumi is that if you're singing her songs you are usually singing songs about emotions, love, peace, sadness, world. Her songs all have themes.
Ayumi Hamasaki- A song for xx (most emotional one), surreal, rainy day (i just love this song), sparkle (strong,fast, and just fun to sing to), next level (awesome), jewel (sweet and slow), momentum (pitch varies), trauma (fast), M (this song made me cried; the words are about the Virgin Mary *the only Christian song to ever hit number one in Japan* and the world and love), boys and girls, Vogue, Is this love (must sing forceful), 1 love (if you want a more raspy tone), Green
"M", which is a prayer to the Virgin Mary; lyrics
http://ayumi.primenova.com/lyrics/m.htmAyumi Hamasaki- M [MV]Ayumi Hamasaki - NEXT LEVEL [PV] ****High Quality****Chistose Hajime is awesome as well, since her voice is known to cause relaxation.
怪 ayakashi 元ちとせ - 春のかたみ - [真人PV]This is the only Namie song I like...
Never End-Amuro Namie.WMVOther recommendations
Utada- Sakura Drops
Rin- Sakura (very traditional Japanese song)
Crystal kay- Kitto Eien Ni
Ai Otsuka- Momo No Hanabira, Cherish, Planetarium