Después de chocar con su hermana pequeña, Kyosuke encuentra un DVD de anime que contiene un juego para adultos. Kyosuke pronto descubre que el juego le pertenece a Kirino y le pide explicaciones al respecto.

Al darse cuenta de que Kirino no tiene nadie con quien compartir sus pasatiempos, Kyosuke le pide consejo a su amiga de la infancia, Manami Tamura, quien le sugiere que intente que su hermana haga algunos amigos otaku por Internet.

Kirino empieza a salir con sus nuevas amigas otaku y se sorprende al descubrir que no tienen que preocuparse por ocultar sus pasatiempos.

On the way home from an enjoyable Summerket. They bump into Aragaki Ayase, Kirino's best friend.

Kyousuke is asked about his relationship with Manami by his friend, Akagi. Akagi is exasperated when Kyousuke answers that, although they don't have a romantic relationship, he doesn't want her to be taken by anyone else.

Kirino has been acting strangely antsy for the past few days. The reason is that the little sister game she ordered hasn't arrived yet.

Sent out to buy groceries by his mother, Kyousuke bumps into Manami at the supermarket. They get to talking, and they eventually arrange for Manami to come visit for the first time in ages.

Ever since the events of the previous episode, Kyousuke has been nervous about his improved relationship with his sister.

One morning, Kyosuke is surprised to find Kirino behaving politely to him. That evening, while Kyosuke worries about whether she is forcing an act in front of everyone, Kirino uses her final life counseling session to ask Kyosuke to buy her an eroge that is launching at midnight in Akihabara. As Kyosuke gets in line, he runs into his classmate, Kōhei Akagi, who is buying a yaoi eroge for his own sister. Kyousuke, after realizing that the trains are no longer running, manages to convince one of the other customers to lend him his bike so he can ride back home. After Kyosuke gets back home with the game, Kirino asks him to play with her. She then shows him all of the medals and report cards with bad grades she had received throughout the years. The next morning, Kyosuke learns that Kirino has left home for America for track and field training. In the beginning of the new school term, Kyosuke meets up with Kuroneko, who would be attending his school as his underclassman.

As Ruri and Sena's game is bashed on the Internet they decide to work harder towards making a better game. As Kyousuke prepares to go home he receives a text message from Kirino telling him to throw away her collection of eroge and anime goods! Kyousuke contacts Ayase who confirms Kirino hasn't been in contact with her since she left either. Kyousuke then meets up with Ruri who encourages him to fly to America to find the root of Kirino's problem—and before the boy leaves she puts a special jinx on him.