Ep 5. My Little Sister's Best Friend Can't Be This XX

Kyosuke's little sister, Kirino, has always been secretive about her anime and eroge hobby. In this episode, her best friend Ayase discovers Kirino's collection accidentally and is shocked by it. Ayase tries to persuade Kirino to get rid of the anime and eroge saying that those things are sinful. Kirino, however, gets angry with Ayase for her close-mindedness. Meanwhile, Kyosuke tries to find a way to help the two make up, as he doesn't want Kirino to lose her best friend.

Kyosuke and Kirino are enjoying a quiet night at home together, playing a dating simulation game together. However, their enjoyment is cut short when Kirino realizes that she has forgotten to return the eroge game she borrowed from Ayase. Kirino panics and rushes out of her room to Ayase's house, leaving Kyosuke behind.

When Kirino reaches Ayase's house, Ayase accidentally discovers Kirino's hidden hobby - anime and eroge. She is shocked and upset, and tells Kirino that she thinks anime and eroge are sinful. Kirino is furious with Ayase's close-mindedness, and the two have a heated argument.

Meanwhile, the next day at school, Kyosuke receives a message from Ayase asking to speak with him after school. Kyosuke meets with Ayase, who asks him for advice on how to repair her friendship with Kirino. Kyosuke knows that Kirino would never forgive Ayase if she found out that Ayase had looked through her things, so he tells Ayase to apologize sincerely for being close-minded instead.

Ayase takes Kyosuke's advice, and expresses her regret for being so judgmental towards Kirino's hobby. She explains that she doesn't understand the appeal of the things Kirino is interested in, but she is willing to learn more about where Kirino is coming from. Kirino accepts Ayase's apology and the two are able to repair their friendship.

In the end, Kirino and Ayase are able to reconcile and remain close friends. Kyosuke is happy that he was able to help the two girls work out their differences and that he was able to keep Kirino from losing her best friend.