Ore no Imouto ga Konnani Kawaii Wake ga Nai.

Kirino Kousaka returns to Japan and resumes the secret otaku life that first pulled her brother Kyousuke into her world. Their relationship remains prickly despite everything he has done for her, while Kuroneko's increasingly direct feelings toward Kyousuke add a new tension to the group.

As Kirino, Kyousuke, Kuroneko, Ayase, Saori, and their friends grow closer, casual hobbies and sibling arguments give way to choices that can no longer be dismissed as jokes. Kyousuke must finally recognize how his actions affect the people around him, while Kirino confronts feelings she has spent a long time refusing to name.