Kirino Is Kyousuke's younger sister and the youngest of the two siblings of the Kousaka family. She is an overachiever who seemingly lives a perfect life and is idolized by almost everybody. However, she keeps a big secret to her family — that she is an avid otaku and a fan of adult-rated games, especially those involving brother-sister dynamics. Her favorite TV series is Stardust Witch Meruru.

Kyousuke's discovery of this secret led Kirino to introduce him into the world of an otaku. 