Toradora!

At the restaurant where Minori works, Yuusaku arrives with the model Ami Kawashima, who is also his childhood friend. When Yuusaku and Ryuuji excuse themselves, Yuusaku shows Ryuuji that Ami is really a conceited and manipulative person, different from her being a self-proclaimed "air head." Taiga soon comes to dislike Ami, and even slaps her in the restaurant. Ami transfers into Ryuuji and Taiga's class, quickly becoming popular with her classmates and the staff. At school she maintains her air head personality. She flirts with Ryuuji and seems to only reveal her true nature to Taiga. Ami tries to make Taiga think Yuusaku hates her now because of how she acted, but Ryuuji assures her that is not the case. (Source: Wikipedia)