Chidori Kuruma is a sixteen-year-old girl who, despite her age, possesses a petite frame and a baby-faced appearance that often leads others to mistake her for an elementary school student. She typically wears her light brown hair in two pigtails, a style that complements her initial impression as a cheerful and childlike individual. However, this exterior conceals a deeper, more serious nature shaped by personal tragedy and a fierce sense of responsibility. As a C-Genomer, she is a descendant of a celestial being, or tennyo, which grants her the ability to transform. In her transformed state, her appearance changes dramatically; her hair becomes dark blue and grows longer, her eyes turn a deep gold, and she gains significant height, becoming taller and more mature-looking.

Beneath her seemingly bubbly and innocent demeanor, Chidori is remarkably mature and protective, a quality born from a traumatic family history. Her parents died in a car accident that also left her younger brother, Shouta, paralyzed from the legs down. Chidori carries a heavy burden of guilt over the incident, as she had insisted on the family outing that led to the crash. This loss made the well-being of her brother the central focus of her life, and she is driven by an unwavering determination to protect him. Her primary motivation is to fulfill Shouta's lifelong dream of flying, a goal she pursues with relentless energy, even if it means resorting to blackmail. She approaches the protagonist, Aya, and her companions, demanding that the celestial maiden Ceres take her brother into the sky.

Chidori's role in the story is that of a catalyst who brings new layers of the central conflict to light. Her arrival in Tokyo to seek Ceres's help soon reveals that she and her brother have a deep and troubling connection to the powerful Mikage family and their clandestine C-Project, a genetic experiment involving celestial descendants. Chidori herself is identified as a valuable Pallas type A, a specific classification of C-Genomer that the Mikage family seeks to use for their own purposes, such as restoring the Hagoromo, a celestial robe. This revelation leads to her capture and she becomes a victim of the conspiracy at the heart of the series.

Her key relationships are defined by her love for her brother and a romantic attachment to Yuhi, a member of the main cast. Her feelings for Yuhi are strong, though they are largely one-sided as he is devoted to Aya. Despite this, Chidori maintains a caring connection with him, even helping to make a new headband for him as a personal gesture. Her relationship with Shouta is the core of her identity; she is his primary guardian and protector, and his fragility is the source of both her strength and her desperation.

Throughout her story arc, Chidori develops from a character who appears simple and driven by a single goal into a tragic figure of sacrifice. Her cheerful facade is consistently shown to hide inner turmoil and a deep sense of responsibility for her past actions. The climax of her personal journey occurs during a rescue attempt. After being kidnapped, she, Yuhi, and another ally are escaping when a guard tries to shoot Yuhi. Without hesitation, Chidori throws herself in front of the bullet, taking the fatal wound. In her final moments, she attempts to confess her love to Yuhi, but she dies before she can complete the sentence, her last words an unfinished declaration of her feelings.

As a notable ability, Chidori, like others of celestial descent, can transform into a more powerful state at will. This transformation greatly enhances her celestial powers, making her much more effective than in her human form. A unique aspect of her transformation is the drastic alteration to her physical appearance, turning her from a girl who looks like a child into a tall, grown woman. This ability and her genetic heritage as a C-Genomer are what make her a target for the Mikage family, ultimately sealing her tragic fate.