The character known as Kuroneko, whose real name is Ruri Gokou, is a fifteen-year-old girl who lives near the main characters and eventually enrolls in the same school. She comes from a family with financial difficulties, and because her parents often work long hours, she takes on the responsibility of caring for her two younger sisters, Hinata and Tamaki, to whom she is deeply devoted. At home, she dresses in normal clothes and focuses on her domestic duties, but in her free time and at social gatherings, she is almost always seen in gothic lolita fashion, an outfit based on a character from her favorite anime, which she wears even in hot weather, sometimes accessorizing with cat ears and a tail.

Ruri’s personality is layered and defined by a sharp contrast between her public persona and her private self. She often adopts the role of a self-styled dark sorceress or the Queen of Nightmares, speaking with an archaic and eloquent vocabulary and claiming to wield dark magic. This behavior is a form of chuunibyou, a delusional fantasy persona that masks her deep social insecurity and introverted nature. While she projects an air of arrogance and confidence, she is actually quite insecure and has difficulty communicating with others outside her small circle. This exterior is a performance, but underneath it, she is a thoughtful, compassionate, and highly creative individual. Her creativity finds an outlet in writing; she writes doujinshi and fantasy novels under pseudonyms, though her very large and complex vocabulary can make her work difficult for even her friends to read.

Her role in the story is largely defined by her relationships. She initially clashes constantly with Kirino Kousaka due to their shared tsundere personality types and differing tastes in anime, with Kirino preferring magical girl shows and Ruri favoring darker, teen-centered fantasy series like Maschera: Lament of a Fallen Beast. Despite their constant fighting, the two genuinely care for each other, and their rivalry matures into a deep friendship and camaraderie, with Ruri providing crucial support to Kirino during difficult moments. She also develops a significant relationship with Kirino’s older brother, Kyousuke. Starting from a place of distance, they bond over their shared rationality and frustration with Kirino. Ruri’s feelings for Kyousuke grow, and she playfully provokes Kirino by calling him Nii-san. They eventually enter a romantic relationship, but Ruri makes the mature decision to break up with him to protect her friendship with Kirino and avoid awkwardness, even though her feelings for him persist.

Throughout the story, Ruri shows significant development. She transitions from a socially isolated otaku to a more engaged individual. She joins her school’s video game club, where her skills prove to be very strong, and she learns to form genuine friendships. Her journey involves learning to balance her otaku identity with her responsibilities at home and at school, ultimately gaining confidence in her social interactions while holding true to her unique identity. One of her notable abilities, aside from her skill at video games and her talent for writing and sewing her own intricate cosplay outfits, is her high level of intelligence and her principled stance on creative work, believing that it must reflect the creator’s authentic self rather than conforming to external standards.