Kyosuke initially claims to prefer a relatively peaceful and simple life, but grows to enjoy spending time with his sister as well as the drama she causes to the point where he becomes lonely when she is not around.Kyosuke helped Ruri make friends and joins the Game Research Club with her during his third year when Ruri becomes his junior.(with a period at the end), aired between April and June 2013.An additional three episodes were streamed online on August 18, 2013.She works as a magazine model and later becomes a novelist, the funds from which she uses to support her hobby.Despite her interests, she states she does not know why she started liking eroge and denies having a brother complex.To Kyosuke's surprise, he finds a hidden eroge inside the case and he soon learns that both the DVD and the game belong to Kirino.That night, Kirino brings Kyosuke to her room and reveals herself to be an otaku with an extensive collection of moe anime and younger sister-themed eroge she has been collecting in secret.
Despite Kyosuke being older, his sister is generally the dominant person in their relationship, with Kyosuke only standing up to her in truly serious situations.
Kyosuke quickly becomes Kirino's confidant for her secret hobby.
The series then follows Kyosuke's efforts to help his sister to reconcile her personal life with her secret hobbies, while restoring their broken relationship and coming to terms with their true feelings for each other. He has a distant relationship with his sister, and feels that this will never change.
Although she states that she only likes eroge because of their cute characters, she shows a perverted side of herself when playing those games.
She uses the screen name Kiririn when with her otaku friends.