Kazue is a young doctor who works at a clinic and serves as the central protagonist of the story. Her background is defined by a chance and horrifying encounter that takes place while she is driving along a dark mountain road one night. She accidentally hits a naked girl with her car, and though the girl seems unharmed, she gets up and flees into the nearby woods. Kazue follows her and is led to an abandoned house, where she does not find the accident victim but instead discovers a different young woman named Yukiko. Yukiko is near death, wrapped in a sleeping bag, and surrounded by disturbing figures. Driven by her medical instincts and a sense of duty, Kazue rescues Yukiko and takes her back to the clinic to recover.

In terms of personality, Kazue is portrayed as a compassionate and responsible individual, which is evident in her decision to care for a stranger she finds in such dire circumstances. Her actions are those of a healer who feels a strong obligation to help those in need. However, she is also shown to be deeply affected by the traumatic events, and a year after the incident, she remains haunted by the mystery of the naked girl she struck with her car. There is a suggestion that she believes this mysterious figure may have been Rei, the missing daughter of a colleague, which adds a personal layer of guilt and concern to her motivation. While her profession requires rationality, the bizarre and unexplainable nature of the case pushes her into a psychological struggle as she tries to separate reality from nightmare.

Kazues primary motivation throughout the narrative is twofold. She is dedicated to the care and recovery of Yukiko, who has been living at the clinic and suffering from amnesia. There is a sense that Kazue is considering adopting the young woman, indicating a deep, nurturing commitment to her patient's future. Simultaneously, she is driven to uncover the truth about the naked girl from the mountain road. Her desire for answers escalates when federal investigators arrive to question her about the incident. They explain the horrifying legend of Tomie, an immortal being of supernatural beauty who causes murder and madness wherever she appears, and who can regenerate from a single cell. This explanation places Kazue at the center of a terrifying conspiracy, and she becomes determined to understand the connection between Tomie, the events in the abandoned house, and the video footage that was recorded there. Her role in the story is that of an ordinary person drawn into an extraordinary and horrifying world, acting as the audience's surrogate who must confront an inhuman evil.

Kazue has several key relationships that define her journey. Her bond with Yukiko is central, as she is both a caregiver and an investigator trying to unlock the secrets of Yukiko's past. The dynamic shifts from one of doctor and patient to something closer to a protective figure and a young woman with a mysterious, and possibly dangerous, connection to Tomie. She also interacts with the federal investigators who bring the Tomie legend to light. Their presence serves to validate her fears and escalate the stakes, transforming her personal quest for answers into a confrontation with a supernatural threat. Although she is a professional, her colleagues at the clinic are also part of her world, as her theory about the naked girl being her colleague's missing daughter suggests an off-screen network of relationships that deepen her personal investment in the case.

Kazues development in the film is marked by a transition from a state of confusion and trauma to one of grim awareness and direct confrontation. Initially, she is a caregiver trying to heal and protect, but as the horrifying truth about Tomies nature is revealed, she is forced to become something else. She moves from being a passive witness to the events to an active participant, realizing that the key to the mystery and her own survival lies in the evidence she possesses, particularly the video camera from the abandoned house. Her development is not about gaining supernatural powers but about finding the courage to face an unstoppable, malevolent force that undermines the very logic of her medical and scientific training. As a human being caught in Tomies ritual of revenge, her journey is one of psychological endurance, where her professional composure is continuously tested by an escalating nightmare. She does not possess any notable supernatural abilities; her strengths lie in her medical knowledge, her compassion, and her determination to protect Yukiko and uncover the truth.