Ore no Imouto ga Konna ni Kawaii Wake ga Nai

The Kousaka siblings have not been getting along for years, due to Kirino being almost perfect, as if getting good grades from the school wasn't enough she also works as a model. Because of the gap, the two rarely talk to each other. One day Kyousuke finds something he never though he would find in his household, an erotic game starring little sister characters inside a magical girl anime DVD case. Kyousuke can't believe it belongs to anyone in the house, especially since his father Daisuke is a strict man who works for police. Kyousuke brings up the subject of magical girl-themed anime at the dinner table, but it's clear his parents have nothing to do with it. That night, Kirino attempts to steal the game back from Kyousuke but he catches her in the act. After he tells her he wouldn't judge her on her hobbies, Kirino brings Kyousuke to her room, and shows him her huge collection, revealing that she is an otaku who adores little sisters and moe characters. With his sisters' hobby exposed, Kyousuke offers to help in any way he can, including keeping it a secret from their family and friends.