Female solo singers, recommendations?

[Sakura_Genki]

I realized lately that my music folder is full of Japanese, mostly male, rock bands, and I think it needs a nice feminine touch.

Artists that I listen to:
Ayumi Hamasaki.
Akino Arai.
Ami Suzuki.
Anna Tsuchiya.
AZU.
Hitomi Shimatani.
Kana.
Koda Kumi.
Leah Dizon.
Nana Kitade.
Nana Mizuki.
Nanase Hoshii.
OLIVIA.
Utada Hikaru.

I'm not really fond of singers like Namie Amuro or Ai Otsuka so anything other than those would be greatly appreciated.