In the series, Kirino is a model student with excellent grades, competent athletic skill and great popularity.

With the help of her older brother Kyousuke, who becomes her confidant, Kirino tries to reconcile her personal life with her secret hobby.

In September 2013, during an interview with Crunchyroll, Tsukasa Fushimi, the writer of Oreimo, was questioned why he made Kirino an otaku and he replied, "Now that I think about it, there might have been something like that going on, but originally I was only trying to make characters that I would find fun.

However, this is a facade and she only reveals her true personality—immature, abusive, and ungrateful with an aggressive, tsundere-like character—to Kyousuke,[6] whom she orders to play her games and care for the characters, only to accuse him of being a pervert and a lolicon.

[7][8] She is secretly an otaku with an obsession for "little sister"-themed eroge, as well as the children's anime series Stardust Witch Meruru.

Although she states that she only likes eroge because of their cute characters, she shows a perverted side of herself when playing those games.

[10] Kirino appears in the crossover story Ore no Imōto to Railgun Collaboration Project!, which features characters from both the Oreimo and A Certain Magical Index series.

[21] Kim Morrissy of ANN made a comparison between Kirino and Eromanga Sensei's Sagiri Izumi, with Morrissy believing that the latter, unlike Kirino, "matches the otaku's image of the ideal little sister: a quiet, doe-eyed girl who exudes moe appeal.

Kim also said, "I think the non-incest aspects to Kirino Kousaka and her sisterly fantasy that make her an appealing love interest are also worth talking about.

Her character combines tsundere with the 'imouto,' or cute little sister archetype, creating an interesting new formula that had audiences thrilled until things got a bit uncomfortable towards the end there.

Regardless, Kirino is the ultimate hot and cold woman with an attitude that switches so fast it can give you whiplash.

"[24] Tim Jones of THEM Anime Reviews strongly criticized Kirino by describing her as being "immensely unlikable", apart from also calling her an "abusive, unfunny creep", as the character's behavior in the anime becomes more hostile as it progresses, remarking that "[t]here is no absolutely no avoiding her selfish, haughty, jackass ways".