Kyōko Hori is the daughter of Kyousuke and Yuriko Hori. Due to her parents' demanding jobs, she assumed significant household responsibilities from a young age, independently managing chores and meals while caring for her younger brother, Souta Hori. This limited her social activities and extracurricular opportunities. Her childhood included a longstanding friendship with Kakeru Sengoku, whom she often teased, resulting in his enduring wariness of her. Physically, Hori stands around 163 cm (5'4") with a slender build. She has wavy chestnut-brown hair, typically worn down at school but tied up at home, and golden-brown eyes, closely resembling her mother's high school appearance. At Katagiri High School, she wears the standard uniform—long sleeves in winter, short sleeves in summer—with a red bow tie and sometimes a vest or blazer. At home, she prefers practical clothing like plain t-shirts, leggings, or jeans, often styling her hair with clips or ponytails. Academically diligent, Hori consistently scores above 90% on exams and maintains a popular, energetic persona at school. Privately, she conceals her demanding home life, including her makeup-free appearance and caretaking role, fearing social judgment. Her personality shifts dramatically when embarrassed or flustered, sometimes reacting violently, like striking her father with a ladle. She exhibits aggressive tendencies during routine tasks such as ear cleaning or nail clipping, causing apprehension. Notably, she displays masochistic inclinations, requesting Izumi Miyamura to adopt an "abusive boyfriend" persona for her gratification, which he does reluctantly. Hori meets Miyamura after he helps Souta following a minor injury. Recognizing each other's hidden selves—Miyamura's piercings and tattoos versus Hori's home life—they agree to mutual secrecy. Their bond evolves from friendship to romance, culminating in Miyamura's proposal during high school and a promise of marriage. Hori experiences intense jealousy over Miyamura's interactions, especially after his appearance change increases his popularity, earning her the nickname "Hannya" (Goddess of Jealousy). She expresses greater concern over his potential attraction to men than women. Post-graduation, Hori marries Miyamura, adopting the surname Miyamura. They later have a son named Kyouhei. Additional details include her double-jointed fingers, allergy to blueberries, dislike of stew and grapefruit, fondness for the anime *Riho's World*, and poor tongue-twister skills despite academic excellence.