Kaname Kenjō is a tall student presenting masculinely, characterized by neck-length black hair swept to the right and sharp red eyes. Her appearance varies between light novels and manga, featuring longer hair in the latter adaptations.

She possesses a domineering, forceful, and devious personality as a member of Spica Academy's student council. Kaname perceives herself as irresistible and dismisses opposing viewpoints. A core aspect of her character is intense jealousy directed at Amane Ōtori, stemming from consistent academic and athletic defeats since their enrollment. This history of loss to Amane fuels a complex resentment intertwined with latent attraction, making self-comparison to Amane a defining element of her identity.

Kaname maintains an explicit romantic and sexual relationship with Momomi Kiyashiki, her primary ally and confidante, forming the series' first explicitly depicted lesbian couple. They frequently share intimate moments, including bathing together in clawfoot bathtubs where they engage in physical affection like kissing. Functioning as primary antagonists, they collaborate on schemes to win the Étoile title for themselves as Spica's representatives. Their tactics focus on disqualifying rival candidate Amane Ōtori by sabotaging Amane's potential partnership with Hikari Konohana.

Her antagonistic methods employ manipulation and force. Kaname orchestrates scenarios to isolate Hikari, such as forging letters from Amane to lure Hikari into private meetings. During these encounters, she uses metaphorical language comparing Hikari to "the moon" and herself to "the sun," physically restrains Hikari, and attempts non-consensual advances, actions consistently interrupted by Amane's interventions. Strategically, she prioritizes self-aggrandizement over cooperation, resorting to obstructionism when thwarted. Despite her manipulative nature, she adheres to a personal code of honor, seeking victory through achievement rather than forfeit.

Manga adaptations depict slightly different motivations; Kaname desires to become Étoile partners with Amane to convey her feelings, believing their pairing represents fate. Her jealousy manifests more intensely regarding Amane's interest in Hikari within this medium.

Character development occurs when decisive defeats diminish her fixation on Amane. She ultimately reconciles with Momomi, shifting focus from rivalry to contentment within their relationship, highlighted by a satisfied embrace during the Étoile election conclusion. Supplemental personality assessments categorize her as an ENTJ (8w7) in Myers-Briggs frameworks.