Ore no Imōto ga Konna ni Kawaii Wake ga Nai
Volume 14: Ayase If Route

Kyosuke Kosaka is an ordinary 17-year-old boy who lives in Chiba, and who has had a terrible relationship with his sister Kirino in recent years. Since he can remember Kirino has been quite cruel to him and despises him. Now, being 14 years old, it seems that this type of relationship will continue like this.
However, one day, Kyosuke finds a DVD with a magical girl anime lying on the doorstep of his house. To his surprise, what was actually inside the box was an eroge (an adult game) and he soon discovers that it belongs to Kirino. Fortunately, it seems that this fact could be the trigger for a reconciliation between the two.