Matsutoya Yumi
Probably the most legendary jpop female artist in activity... From body language, to theatrics, to stages, to choreography, to outfits to overall sound, she is an influence. Ayu two of her songs.
Seiko Matsuda
The equivalent of Ayu during the 80's and the first big artist to use the kawaii image... Everytime Ayu goes mid-aged 8 years old girl or living birthday cake, she is going Seiko.