Ore no Imouto ga Konnani Kawaii Wake ga Nai

Synopsis

After running into her at the supermarket, Kyosuke invites Manami over to his house to help him make lunch. However, Kirino is not too pleased with having Manami around and makes various plans to hamper her visit, ranging from giving her arduous tasks to laying embarrassing pornographic traps in Kyosuke's room. Later, Saori holds a "personal harem party" for Kyosuke with Kirino, Kuroneko and herself dressed as maids. There, Kuroneko shows off a perverted manga with characters based on Kirino and Kyosuke, and later even starts calling him "nii-san" much to the ire of Kirino. Kyosuke has a small outburst at Kirino for her behavior, until she gives him a present, saying she is grateful for all his help.

(Source: Wikipedia)