Isabelle is the French adaptation of the character Tomiko from the original Japanese series. She is a human character from a wealthy background, embodying the "Rich Bitch" archetype. Initially, Isabelle acts as a rival to the protagonist, competing for the affections of Akira (renamed Anthony in French). This rivalry defines her role throughout the first half of the series.

Midway through the narrative, Isabelle loses her romantic interest in Akira/Anthony. This shift ends her antagonistic rivalry with the protagonist. By the series conclusion, her relationship with the protagonist evolves into a more amicable dynamic, potentially reaching friendship. No additional background, developmental arcs, or appearances in other official media are documented for this character.