For the past seven years, Kyousuke's relationship with his younger sister Kirino has been nothing but cold. It has come to a point where the siblings only exchange greetings with each other. But one day, Kyousuke finds a moe anime DVD lying in the entrance hall of his house. As his interest piqued, Kyousuke looks for the owner, only to discover it belongs to his very own sister Kirino. Shocked as Kyousuke was, this was just the beginning to the surprises that lie ahead Living in the shadow of his prodigious younger sister, Kyousuke Kousaka had a normal lifestyle until he accidentally finds out that Kirino hides a dark and embarrassing secret. In addition to being smart, pretty, and popular; Kirino Kousaka is also an obsessive consumer of anime and eroge (adult computer games). After being assured that Kyousuke is committed to not mock her and keep this concealed from their parents, she starts to share a bit of her world with him. Kirino faces several problems as she tries to keep appearances and balance her exemplary school life with her hobbies. Her brother then becomes a crucial ally while dealing with all the difficulties that lie ahead.