Claire Rouge is the leader of Team Scarlet and an elementalist using the flame spirit Scarlet, which can transform into a whip. She is under the "Raven Class" which is infamous for being a class for problem students such as herself. Her reputation of being a sister of a traitor often led her to be alienated by most students, causing her to be on her own for the most part, and leading her to seek a more powerful spirit, which is why she never stops pestering Kamito to be her contracted spirit, despite the latter's refusal.

She used to be a noble who is part of the "Duchy of Elstein"; however, she dropped her original family name four years after the incident where her sister Rubia Elstein (The Calamity Queen) was involve in the destruction of the Ordesia empire.

She is friends with Rinslet, although their day-to-day interactions are more like those of rivals. Rinslet often makes fun of Claire's flat chest during their arguments.