Kirino Kousaka embodies the ideal student, her appearance equally enthralling. Her grades hover near perfection, and to cover personal expenses she models professionally alongside her best friend Ayase Aragaki, who despises liars and all otaku culture. Yet Ayase remains unaware that Kirino harbors a deep, long‑hidden secret destined to emerge soon.
One ordinary day at home, Kyousuke, Kirino"s perfectly average brother, stumbles upon an erotic game that belongs to his seemingly flawless sister. Facing potential scandal, Kirino silences him and simultaneously introduces him to the world of eroge and anime. Through her guidance, Kyousuke meets gothic‑lolita Ruri Gokou and glasses‑wearing otaku Saori Makishima, launching an entirely new lifestyle. As he becomes increasingly involved in his sister"s clandestine life, keeping it secret grows ever more difficult, threatening both their reputations and the fragile harmony of their family as they navigate the challenges of adolescence and unexpected revelations in a world that shifts rapidly today.