A young woman who once dated both Okayasu men, Morika has a grudge against Ryo and tries to use Kairi against him.    *Wikipedia

Peach Girl is about an average high school girl, Momo Adachi, who everyone thinks is a beach bunny / slut because of her tanned skin. The actual reason she is so tanned is because she was on the swim team and tans very easily. She likes a boy, Toji, who she heard only likes non-tanned girls. This causes her to question who she is and have low self esteem. She spends a lot of time trying to remake herself into the girl she believes he wants. However, she has a friend, Sae, who likes to go behind Momo's back and make her life terrible, mostly by trying to take Toji away from her. All the while there's another boy, Kairi, who is in love with Momo.
 
(Source: Anime News Network)

It's not easy being beautiful. The envy, the jealousy, the vicious rumors spread by your best friend. That's life for young Momo. While everyone thinks that Momo is a wild party girl, the reality is that she is shy and lonely. Can Momo confess her love to her classmate, Toji, or will her best friend Sae steal him away. It's a bittersweet drama of growing up and fitting in that will charm readers everywhere. (Source: Tokyopop) 
Volumes 1-8: Peach Girl; Peach Girl Authentic (2nd English Edition) 
Volumes 9-18: Peach Girl - Change of Heart