Kotonoha Katsura, eldest daughter of the wealthy Katsura family alongside her father, mother Manami, and younger sister Kokoro, attends Sakakino Academy as a first-year in Class 1-4. She holds positions as class representative and student council member. Her childhood involved extensive training in piano, ballet, Japanese dancing, and calligraphy, all discontinued upon entering high school. Socially isolated due to jealousy from peers like Otome Katou and Nanami Kanroji, she remained friendless until encountering Makoto Itou and Sekai Saionji. Physically, she possesses pale skin, maroon or chestnut eyes, and straight purplish-black hair extending past her waist. Her figure appears notably mature for her age—slender with measurements of 102-60-84 cm at 156.7 cm (5'1") tall. Outfits vary across media: school uniforms in *School Days* and *Cross Days*, a red summer dress in *Summer/Shiny Days*, and swimwear such as a cyan bikini or low-cut white one-piece. Initially intelligent, gentle, polite, and reserved, her personality shifts dramatically through romantic experiences. She exhibits intense fear of male physical contact, causing early awkwardness with Makoto. Her devotion evolves into obsessive dependency. When betrayed or abandoned, she descends into a "yandere" state marked by lusterless eyes, delusions, and extreme violence—including suicide attempts, murdering rivals, or manipulating situations through sexuality. She forgives Makoto’s infidelity if he stays, even accepting multiple partners, but ruthlessly eliminates perceived threats. In the *School Days* visual novel, her development hinges on comfort with sexual activity. Routes range from retaining shyness to becoming sexually aggressive or manipulative, using her body to secure Makoto’s loyalty. Endings include mutual relationships, bisexual attractions toward Sekai, or violent outcomes where she kills Sekai or herself. The anime adaptation follows a linear tragedy: after Makoto abandons her for Sekai, Taisuke Sawanaga rapes her during the school festival. Briefly reuniting with Makoto, she witnesses Sekai murder him; she then decapitates Makoto and kills Sekai to disprove Sekai’s pregnancy, last seen cradling Makoto’s head on a boat. Manga iterations diverge: the *School Days* manga depicts her accidentally slashing Makoto while attacking Sekai, later dying after Sekai stabs her. In *Cross Days*, she remains unaware of Yuuki Ashikaga’s crush, stays devoted to Makoto, and accuses Yuuki of theft when warned about Makoto’s infidelity. *Summer/Shiny Days* features her as a pursuable heroine, with routes involving her, Manami, or Kokoro separately or in harem dynamics with Makoto. OVAs include *Valentine Days*, showing her making occult-themed chocolate for Makoto, and *Magical Heart Kokoro-chan!*, parodying her as "Magical Word"—a sword-wielding magical girl. Her hobbies include extensive reading in libraries or bookstores and practicing iaido, which she employs in violent endings. Though skilled in specialized lemonade preparation, she struggles with general housekeeping and cooking. Cultural activities like calligraphy ceased in high school. Reception solidified her as a yandere archetype, earning nicknames like "Kotonoha-sama" in Japan and "Goddess Kotonoha" in Chinese-speaking regions. Her character design and emotional trajectory remain focal points in franchise analyses.