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.

Kuroneko (real name: Ruri Gokou) enrolls in Kyousuke's school, and Saori feels downhearted that she hasn't heard from Kirino. Kyousuke notices that Ruri is having trouble making friends due to her personality, so he decides they should try a membership at their school's Games Research club where the boy meets two other persons he never expected to be there as well.

With Sena and Kuroneko constantly quarreling in the Games Development club, the club president decides they'll have to write a game together and submit it to an online contest. Both girls have different concepts about the game's theme, so they'll both present them to the club whose members will then decide by majority vote whose concept will have to be implemented. And Kyousuke, with no programming skills thus acting as supervisor for the team, suggests to write an eroge—in order to have less competition and a better chance to win the contest.

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.