Just to help you, here's a summary of what's being recommended
KOKIA
Emi Hinouchi
Hitomi Shimatani
Angela Aki
Shoko Nakagawa
sifow
B'z
Maki Goto
Utada Hikaru
ICONIQ
Rina Aiuchi
Mai Kuraki
Chihiro Onitsuka
melody.
BONNIE PINK
Crystal Kay
ayaka
Ami Suzuki
Mika Nakashima
OLIVIA
Fukuhara Miho
hiromi
Thelma Aoyama
Yu Yamada
Mini
SAWA
JUJU
Anna Tsuchiya
Kanon Wakeshima
Hidemi Uematsu
GND
Nana Mizuki
BENI
Ikimono Gakari
Aya Kamiki
Tommy heavenly6 / february6
Meisa Kuroki
Akiko Shikata
Chara
Kimura Kaela
How I don't envy you
Are mostly into R&B/Pop/Electro/Dance-ish type music?