Kyoka Kanejo is a 15-year-old transfer student from America joining Takizawa High School during the characters' second year. Born into extreme wealth, she identifies as a perfectionist, excelling academically and demonstrating talent in diverse activities like modeling, cooking, and sports. She notably outperforms classmates in swimming, challenging Yamada's status as the fastest in their class. Kyoka possesses distinctive plum-colored shoulder-length hair, purple eyes, a pale complexion, C-cup breasts, and long legs, often depicted with comical sparkles around her head. She wears the standard school uniform: a V-neck jumper, white collared shirt, dark navy blue skirt, and knee-high socks.

Kyoka harbors an intense brother complex focused on her older brother Keiichi Kanejo, a student at Harvard Business School. This fixation manifests in a private room within her mansion dedicated entirely to Keiichi, filled with his photographs and personal items. Publicly, she positions Yamada as her primary rival after placing second to her in the school's beauty pageant. Kyoka openly declares her intent to steal Yamada's boyfriend, Takashi Kosuda, as part of this rivalry, though her actions serve more as competitive provocations than genuine romantic interest. Their rivalry extends to academic and athletic contests, including swimming races and other school events.

The meaning of her name reflects her persona: "Kyō" (京) translates to "capital city," and "ka" (香) means "fragrance." Kyoka's character development centers on navigating her rivalry with Yamada while concealing her familial obsession. Her brother complex sees no significant evolution or resolution within the source material, and she maintains her competitive yet socially polished demeanor throughout. The character appears exclusively in the main series, with no presence in spin-off media or extended adaptations.