Kikyō Kushida is a student at the Tokyo Metropolitan Advanced Nurturing High School, where she is a member of Class 2-D during her second year. She is a young woman of average height with short, beige-colored hair and distinctive crimson gradient eyes. On the surface, she presents herself as a cheerful, energetic, and exceptionally friendly individual. Her public persona is that of a helpful and gentle girl who aims to be friends with everyone, a goal she pursues with great persistence. This affable nature has granted her tremendous popularity and influence not only within her own class but across the entire school, including among upperclassmen.

Beneath this flawless exterior, however, lies a radically different personality. Kikyō secretly harbors a dark, manipulative, and deeply spiteful side. This hidden self is the result of a traumatic incident during her third year of middle school, which she attended alongside her classmate Suzune Horikita. At that time, Kikyō maintained her friendly facade online but would privately vent her frustrations by posting criticisms of her classmates' flaws and secrets on a social media account. When this account was discovered, her classmates turned on her, branding her a hypocrite. In response, she vengefully revealed every secret she had been trusted with, causing widespread mutual hatred and a class-wide boycott of school. This event cemented her belief that her social standing depends entirely on maintaining a perfect image, and she entered high school determined to protect that image at any cost. Because Horikita Suzune attended the same middle school and might know of her past, Kikyō developed an intense and obsessive hatred for her, viewing her as a threat that must be eliminated.

Kikyō’s primary motivation throughout the first year and into the second is to expel Horikita and anyone else who discovers her secret, such as Kiyotaka Ayanokōji. She initially cooperates with the antagonistic Kakeru Ryūen, leaking information from Class D to him in exchange for his help in targeting Horikita. Her role in the story is that of a recurring antagonist and a significant internal threat to her own class, as her personal vendetta often overrides any loyalty to her classmates.

Her key relationships are defined by her dual nature. Her friendship with Yōsuke Hirata is genuine on the surface, as they are both popular leadership figures in the class. However, her relationship with Kiyotaka Ayanokōji is fraught with tension. After he accidentally witnesses her true, malicious personality, she threatens to accuse him of sexual assault to ensure his silence. Over time, as he consistently foils her schemes, her hatred for him grows to match that for Horikita, though she also becomes increasingly wary of his true capabilities. The most complex relationship is with Suzune Horikita. While Kikyō publicly tries to befriend her, she secretly schemes for her expulsion. This hatred stems not just from fear of exposure but also from a twisted form of jealousy, as she resents Horikita for being straightforward and having no hidden side to hide.

Kikyō undergoes significant development during the second year, particularly during the Unanimous Special Exam of the first semester. In a critical turn of events, Ayanokōji orchestrates a situation that publicly exposes her secret dual personality to the entirety of Class D. Facing certain expulsion and social ruin, she reverts to her old middle school behavior, preparing to reveal all her classmates' secrets out of spite. However, in a shocking move that defies expectations, Horikita Suzune intervenes and forcefully advocates to protect her from expulsion. This event marks a turning point. While she continues to contribute to the class and maintains a complex relationship of both antagonism and cooperation with Horikita, she is forced to reevaluate her position. She continues to participate in competitions as a core class member, albeit sometimes only at a bare minimum, and her fear and wariness of Ayanokōji solidify into a grudging acknowledgment that he is not someone to be made an enemy of.

Kikyō possesses several notable abilities, with her greatest weapon being her exceptional social and emotional intelligence. Her capacity to build a vast network of trust and gather sensitive information from almost anyone is a formidable tool she uses for manipulation. While not a primary academic or physical powerhouse like some other characters, she is cunning and resourceful, using her popularity as a shield for her covert operations. Her charisma and influence remain potent assets, making her a dangerous antagonist even after her true nature is revealed, as she retains the ability to mobilize her peers when it serves her purpose.