Onyanoko Darling 

Ritsu had always hated her rival Kanzaki, a cram school classmate, since he seems to be beat her in everything. On the other hand, she loves her beautiful best friend Yuuna. When Ritsu and Yuuna was asked if there is a boy they like, Yuuna had suprisingly answererd yes! Who is the boy Yuuna likes- could it be Kanzaki? But wait, that's impossible, because-- Note: Includes two extra chapters.