Kyōko Hori attends Katagiri Senior High School in Class 3-1, maintaining a distinct contrast between her public and private personas. At school, she cultivates a popular and well-groomed image, excelling academically with test scores consistently above 90% and projecting a sociable, energetic demeanor that fosters a positive atmosphere. Her school appearance includes light makeup and chestnut-brown hair worn down, paired with a seasonal uniform typically consisting of a white button-up shirt, skirt, knee socks, and loafers, often with gym shorts underneath. Outside school, Hori shoulders domestic responsibilities due to her parents' frequent absence, caring for her younger brother Souta, managing household chores, and cooking meals. In this setting, she forgoes makeup, wears practical clothing like plain t-shirts and leggings, and ties her hair in ponytails, buns, or braids. This double life remains a secret until classmate Izumi Miyamura discovers her true self after returning Souta home. They mutually agree to conceal each other's secrets—his piercings, tattoos, and non-otaku personality—forging a close bond that evolves from friendship to romance. Hori's personality blends diligence with volatility. She exhibits intense responsibility in academics and homemaking but reacts violently when embarrassed or flustered, such as striking her father with a ladle. She displays aggression during routine activities like ear cleaning or nail clipping, wielding tools "like lethal weapons," causing apprehension. Within her romantic relationship, she harbors masochistic tendencies, requesting Miyamura to adopt an "abusive boyfriend" persona—shouting at or lightly hitting her—which she finds refreshing due to his typically gentle nature. Jealousy defines aspects of her interactions, particularly after Miyamura's physical transformation increases his popularity. She earns nicknames like "Hannya" (Goddess of Jealousy) for intense reactions to female attention directed at him. She expresses greater concern over the possibility of Miyamura being attracted to men, explicitly stating she would prefer infidelity with a woman over a man. Her background involves long-standing self-reliance, leading to separation anxiety during Miyamura's brief absences; this dependence lessens as their relationship solidifies. She shares a supportive friendship with Yuki Yoshikawa and navigates complex dynamics with childhood friend Kakeru Sengoku and admirer Tōru Ishikawa, whom she rejects romantically. Key details include her height (163 cm), dislike of stew and citrus flavors (except mikan), allergy to blueberries, fondness for the anime *Riho's World*, being double-jointed, and struggling with tongue twisters. Post-graduation, she marries Miyamura, taking the name Kyōko Miyamura, and they have a son named Kyouhei.