Chifuyu Rehn Kuroda, a half-Japanese student at Keimon West Private High School, sports magenta bob-cut hair and purple irises. Her notably short stature includes an A-cup bust measurement. Academically dominant, she skipped entrance exams to enroll and perpetually ranks first across all subjects. Athletics remain her weakness, yet she harbors a competitive spirit and intense aversion to defeat.

Her personality radiates high self-esteem and a tendency to meddle in others' affairs. She nurses recurring envy toward classmates' physical development, particularly fixating on Akira Todo's larger bust size. This jealousy fuels antagonistic encounters: a volleyball challenge where Akira's spike knocks her unconscious, and a pool incident where Chifuyu exposes Akira's breasts, only to be thrown into the water. Their clashes lack genuine hatred, eventually settling into coexistence.

Chifuyu relentlessly pursues Shota Doi, one of the few remaining immune males. She crafts a chemical formula to induce his affection and directly demands mating, though Shota deflects due to her youthful appearance. Undeterred, she challenges him to a swim competition, announcing herself as the "Lightning of Muenchen" before stumbling into the pool and nearly drowning.

Her older sister, Maria Kuroda, reunites with her at a mating facility after a terrorist attack on their school. Chifuyu questions Maria about mating with another immune male, No. 2—a notion Maria deems absurd. Trivia notes her name derives from the Japanese word for "winter," her blood type is AB, and her hobbies and skills encompass all academic subjects. She openly admires herself but detests exercise. In popularity polls, she ascends from nineteenth to ninth place.