most people have hit a lot of the singers i was thinking of already.
but lets not forget:
Hajime Chitose - she sings in shima-uta style, lots of highs and lows. Great range, good power and control. Shes become rough later on in her career though.
Choi Jin Yi - front woman for kpop band rumble fish. Wicked power, and emotion. Good range tonally and stylistically. Just really fun to listen to!
Natsukawa Rimi - another shima uta singer, but she's a lot cleaner and ....leaner in shima uta style than hajime chitose is. And her voice....just....holy ****. Do you know any other singers whose voice can fill a theatre without a microphone? Her live stuff is incredible. Her albums are still good, but a studio just can't seem to capture her entire voice. INCREDIBLE.