Ore no Imouto ga Konnani Kawaii Wake ga Nai.

Synopsis

After hearing no word from Ruri following their alleged break up, Kyosuke is shocked to learn from Sena that Ruri has transferred schools, later finding her house completely vacated. Troubled by this, Kyosuke comes to Kirino, who gives him his own life counselling and decides to help him search for her in a hot spring town. After they eventually manage to find her, Ruri points out that Kirino hadn't truly accepted her dating Kyosuke, forcing her to confess her true feelings that she didn't want him to have a girlfriend, which was the reason she passed off Kouki as her boyfriend. Kirino states that despite this, she doesn't want to see her brother cry even more than that and wants to get the two back together to repay how much he has supported her over the past year. After Ruri hears all this and a makes a curious remark towards Kyosuke before temporarily passing out, she reveals she is simply moving to a nearby town for family reasons, having only been in the town on vacation, and will still be relatively close to the others. After Kyosuke decides he is probably not ready for a girlfriend just yet, Ruri states the next stage in her plan is for her, Kyosuke and Kirino to get along with each other.

(Source: Wikipedia)