Kinuyo Kasuga holds the position of student council president at Shijo Minami Junior High School, distinguished by long brown hair with trimmed bangs and brown eyes. She consistently wears the school uniform during academic duties and a kimono at home.

Her strict and candid personality drives her leadership approach, particularly in championing merit-based reallocation of school club funding over equal distribution. This principle leads her to deliver an ultimatum to the underperforming boys' soft tennis club, demanding competitive results to avoid dissolution. She deems clubs without achievements wasteful, insisting resources should reward demonstrable effort and passion. Her bluntness manifests in public mockery, such as belittling Kanako Mitsue’s feelings for Maki Katsuragi.

Kinuyo’s upbringing unfolded amid familial conflict within her wealthy household. Her grandmother, Haruhi Kasuga, named her "Kinuyo" (meaning "silk generation"), while her mother, Ryouka Kasuga, despised the name and privately calls her "Ruriha." Kinuyo personally prefers "Kaori." Ryouka forced her enrollment at Shijo Minami—a school for "commoners"—against Haruhi’s protests, intending for Kinuyo to observe ordinary life since "those types of people work for her father." Haruhi condemned the decision, fearing it would turn Kinuyo into a "silly goose" like Ryouka, whom she dismissed as old-fashioned.

Beyond school responsibilities, Kinuyo displays affection for cats. Her surname, combining the characters for "spring" (春) and "sun/day" (日), reflects her family’s prominence.