Charlotte Dunois arrives at IS Academy as a first-year transfer student and France's IS Representative Candidate. Initially operating under the male alias "Charles" to infiltrate Ichika Orimura's circle and extract data on his IS unit, her true identity emerges when the mission collapses after Ichika uncovers her secret. Born to a mistress of Dunois Industry's CEO, Charlotte endured familial neglect until her father, recognizing her IS aptitude, manipulates her enrollment into the academy. Though tasked with sharing Ichika's room to facilitate espionage, she discards the mission, rejecting deception as her emotional bonds with him deepen.

Her visual presentation evolves from an androgynous disguise—long blonde hair secured in a low ponytail—to embracing the academy's female uniform, tailored with a shortened skirt and red-and-white sneakers. Her IS manifests as an orange pendant in standby mode, while a silver bracelet from Ichika, worn on her right wrist, symbolizes their strengthened connection post-revelation.

Maintaining a composed and courteous exterior despite her deceptive origins, Charlotte distinguishes herself by prioritizing Ichika's well-being over romantic rivalry, earning his regard as the most compassionate among their peers. Her tranquil demeanor fractures only when provoked, revealing a chilling "Angel of Death" smile. This maturity coexists with playful impulsiveness—spontaneous wardrobe changes in Ichika's presence or unplanned physical contact spark recurrent comedic tension. Though she frequently labels him a "pervert" after inadvertently creating compromising scenarios, her own actions often precipitate these misunderstandings.

In combat, she masters the Rapid Switch technique and commands the durable Rafale Revive Custom II, later merging it with the third-generation Cosmos to pilot the dual-core Rein Carnation. Beyond battlefield tactics, she channels precision into culinary arts, regularly preparing meals for Ichika.

Her arc traces escalating assertiveness in romantic pursuits—sneaking into Ichika's Kyoto quarters and engaging in group skirmishes over his attention. A childhood defined by maternal closeness and paternal estrangement (only two encounters with her father) fuels her craving for authentic relationships. Ichika becomes pivotal as the first individual to genuinely cherish her beyond utilitarian value.

The "Long Vacation Edition" OVA positions her within summer poolside antics, reflecting her integration into the social group through competitive yet humorous interactions aligned with her established role in collective dynamics.

Charlotte's journey navigates liberation from familial exploitation, self-acceptance, and the complexities of forging trust. Her narrative consistently underscores tactical combat contributions intertwined with empathetic resilience.