In the anime Igano Kabamaru, Agnès is known as Mai Ookubo in the original Japanese version. She is the granddaughter of Ran Ookubo, the wealthy and formidable headmistress of Kin'gyoku Academy. Orphaned at a young age following the death of her parents, Agnès lives with her grandmother in a large house in Tokyo, embodying the poised and proper demeanor expected of a young lady from a prestigious family.

Personality-wise, Agnès is initially characterized by her refined but somewhat conventional nature. She values order, manners, and social propriety, which makes the sudden arrival of the wild, uncouth, and food-obsessed ninja Kabamaru a significant source of culture shock and personal embarrassment. She finds his insatiable appetite and complete lack of urban etiquette to be repulsive and often compares his behavior to that of an animal. Beneath this prim exterior, however, she is a resilient and caring individual who has shouldered the loss of her parents with grace.

Agnès’s primary role in the story is as the love interest and emotional anchor for the protagonist, Kabamaru. While he immediately develops a powerful and obvious crush on her, she initially rejects his advances with disdain. Her motivations shift from simply trying to maintain her social standing and personal space to a deeper, more complex journey of seeing past Kabamaru’s rough exterior to his genuine kindness and bravery. She is not merely a passive prize but a catalyst for Kabamaru’s growth, forcing him to confront the differences between his mountain upbringing and the complexities of human relationships.

Her key relationships define her arc. The most significant is her evolving bond with Kabamaru. She starts by finding him unbearable, but as he consistently protects her and demonstrates a pure, if clumsy, heart, her feelings transform. A pivotal moment occurs when he rescues her during a mountain blizzard and selflessly cares for her in an isolated shack, an event that allows her vulnerability to surface and leads her to recognize her own romantic feelings for him. Her relationship with her grandmother, Ran, is one of mutual respect and dependence, though Ran’s mischievous decision to bring Kabamaru home often puts Agnès in trying situations. She also interacts with other students at Kin'gyoku Academy, including the student council president Shizune Mejirou, who often manipulates Kabamaru, placing Agnès in the role of a concerned observer.

Agnès undergoes significant development from a haughty and embarrassed schoolgirl to a compassionate and determined young woman. She moves from passive rejection of Kabamaru’s world to actively confronting her own feelings. In a demonstration of her newfound courage, she confesses her love to Kabamaru, promising to wait for him when he decides to return to the mountains with his grandfather to continue his ninja training. This act shows her growth from a girl concerned with appearances to one who values genuine connection and loyalty.

While Agnès does not possess ninja abilities or engage in physical combat, her notable abilities lie in her emotional intelligence and her role as a grounding force. Her presence often serves to elevate the stakes of the narrative, as her safety is frequently a primary motivation for Kabamaru’s actions. In extended or later continuities, the bond she forms with Kabamaru ultimately leads to marriage, and they have a son together, cementing her role as the enduring partner who helped bridge the gap between his wild past and a stable future.