Thanks for more recommendations, guys!
A few quick comments:
I've been a fan of Chihiro Onitsuka since her debut

Everyhome is one of the best singles released this year, I think.
I've also always liked Jun Shibata since her debut, but her music is so hard to find...
Angela Aki has for me been last year's best discovery. In my opinion, she released last year's best album (Home). I'm not too happy about her last two singles, though. Maybe the new album will prove me wrong!
Will check out: Eri Nobuchika and Two-Mix.
Still ambivalent about Leah Dizon