 If you liked
Kimi ni Todoke
|
 ...then you might like
Heroine Shikkaku
|
Both feature a popular guy who falls in love with an unpopular girl.
Both have a beautiful rival that tries to steal the male protagonist´s heart, the difference is, while KnT is told by the perspective of the heroine, HS is told by the perspective of the rival.
Also the protagonist of HS greatly resembles Kurumi from KnT in looks and personality.