Kaoruko Nijouin is a second-year student at Yuraginozaka High School, hailing from the wealthy Nijouin Conglomerate family. Academically accomplished, she excels in her studies and demonstrates proficiency in martial arts and the fine arts. Her personality combines elitist tendencies regarding anime fandom with genuine kindness toward her friends, manifesting in interactions where she upholds high standards for otaku culture while staunchly supporting those close to her.

Physically, she stands 162 cm tall and weighs 53 kg, with body measurements of 82-56-84 cm. She possesses long black hair reaching her waist and distinctive blue-green eyes. Born on November 10th, her zodiac sign is Scorpio and her blood type is B. Her theme color is blue.

Within the narrative, Kaoruko participates in missions to protect fictional worlds from viral corruption that erases cultural memories. Alongside fellow Rabbit Shed Shop members, she ventures into infected story worlds to combat memory-destroying viruses, wielding dual weapons in combat. A notable mission occurs within the world of "The Rosy Maidens," where her efforts help restore the series after its characters' outfits are corrupted into tracksuits. This mission reinforces the importance of the series in her friendship with Michi Edogawabashi and Yuina Machiya.

Her hobbies include secretly watching anime, a pursuit necessitated by her family status. She expresses strong preferences, showing particular dislike for slackers while valuing perfection. Her actions consistently reflect a balance between upholding high cultural standards and maintaining loyal friendships through collaborative efforts to preserve otaku culture.