Ore no Imouto ga Konnani Kawaii Wake ga Nai.

Synopsis

A party is held for Kyosuke at his new apartment and Kirino arrives there just to find Manami, and despite her animosity towards her brother's classmate, she decides to put it aside for his sake. Ayase, Ruri, Saori and Kanako also attend the party, but chaos ensues when they start arguing about who among them should take care of Kyosuke as he prepares himself for the mock exams and Kirino settles it by appointing Ayase to the task. The mock exams come and thanks to Ayase's support, Kyosuke manages to earn an A grade and the right to return home. As he is preparing to move back, Ayase confesses her feelings for him, but he politely declines, revealing that he is already in love with someone else. Instead of kicking him like she usually does, Ayase kisses Kyosuke on his cheek and bids farewell to him.

(Source: Wikipedia)