I tried to find this by searching through the 'Music' categories but failed to ...
I can only remember that manga is about a girl(A) who is a singer with cute image. She likes a boy but he had a girlfriend already, a normal girl. Then in a music show that boy saw A potential to become a great singer. Later when she became famous for her talent, she became great friend with his girlfriend. Her character is a bit bitchy at first but good inside, like tsundere.
I remember a scene where she cried on stage because of some dirty tricks by other singer, then she ran to the hospital for her friend.
That's all I can remember now ;-; This one is quite old. Help please I want to read it again so bad !!!!!

Could it be Tenshi no Uta or Torokeru You na Kiss wo Kanadete? I've never read those manga myself, just tried to do some searching.

** Shoujo & Romance Manga Lover || Cleaner-Typesetter**
[img]http://i.imgur.com/5h6vq7w.gif[/img]