Kazumi Takiura is an eighteen year old high school student and aspiring model who becomes a central figure in the life of the protagonist, Jun Fudo. She is characterized by her friendly and polite demeanor, which invites a sense of warmth from those around her, alongside a stubborn determination to forge her own path. This ambition is focused on a career in professional modeling, a goal she pursues with such passion that she disregards advice from her peers and even her idol, Jun, and abandons the idea of attending college. Her drive is deeply rooted in her troubled past, as she had a difficult relationship with her parents before their tragic deaths, leaving her to desperately seek attention and connection from others.

Kazumi first meets Jun at a modeling agency, where she declares her wish to follow in Jun's footsteps. After a Devil Beast kills her parents and destroys her home, a traumatized Kazumi is taken in by Jun, and the two begin living together in Jun's apartment. In this shared space, their relationship deepens significantly, with Kazumi treating Jun like an older sister and becoming fiercely loyal to her. She becomes suspicious of Jun's frequent and exhausting late-night absences, which Jun claims are work-related, and she often worries that Jun will one day leave her behind.

As the series progresses, Kazumi's admiration for Jun evolves into a deep, romantic love. Her world is shattered when she is captured by the Crusaders and learns the truth: Jun is the Devilman Lady, a being with demonic powers who fights Devil Beasts. Far from being horrified, Kazumi accepts Jun completely, her love and respect growing as she understands the burden Jun carries. In the climax of her character arc, Kazumi awakens her own Devilman abilities due to prolonged exposure to Jun. In this transformed state, she grows taller, sprouts bat-like wings, develops feline eyes, sharp fangs, and gains superhuman strength. She uses these powers to fight alongside Jun, demonstrating her unwavering commitment.

Ultimately, Kazumi is mortally wounded in battle against the powerful Naberius. In her final moments, she shares a heartfelt confession of love with Jun, reaffirming her feelings and telling Jun to live on and hope for a better future. Kazumi is later cremated by a grieving Jun. Her memory persists, however, as Jun later sees a vision of her in the depths of Inferno, where Kazumi is the only soul who encourages her not to give up. This vision and the love she represents become a crucial source of strength for Jun in her final battle.