Kozue Naruse is a student at Waldstein Academy and a classmate of both Maya Kumashiro and Ami Kuroki. She is easily recognizable by her short brown hair, brown eyes, and the glasses she wears. Her defining trait is an intense fascination with the occult, which she pursues with unflagging enthusiasm. This passion drives her to spend much of her time researching supernatural phenomena, collecting purported artifacts, and eagerly seeking out any opportunity to have a firsthand paranormal experience.

Her personality pairs an earnest, almost childlike wonder with a scatterbrained and somewhat ditzy nature. She often overlooks practical details or academic responsibilities, reflected in her low grade average. Despite her occasional clumsiness and naive trust in dubious occult claims, she approaches every mystery with boundless curiosity and a sincere belief that the supernatural is real and wondrous. That determination leads her to take extreme measures to prove the existence of the occult, such as volunteering for a near‑death experiment during a classroom demonstration, hoping to glimpse the afterlife.

Kozue’s role in the story is that of a supportive but frequently endangered character. Her relentless quest for occult encounters repeatedly places her in the center of dangerous situations. She has been possessed by a vengeful spirit, abducted by a mothman-like creature during a field incident, and lures phenomena toward her simply by her refusal to ignore anything mysterious. As a result, she often becomes a target of the very forces she adores, requiring rescue by Maya and Fumiaki Uchida. Yet these misadventures also provide crucial leads in the search for the Nostradamus Key, making her unintended involvement a recurring catalyst in the main plot.

Her relationships in the academy are defined by her connections with Maya and Ami. She shares a friendly camaraderie with Ami, but her dynamic with Maya is more complex. Kozue looks up to Maya with admiration mixed with a desire to convince Maya—a known skeptic of the occult—that the supernatural is real. She frequently runs to Maya with odd objects, like a rust‑proof spoon she believes is an out‑of‑place artifact, only for Maya to dismiss them as mundane. This pattern becomes a comedic routine but also deepens Kozue’s resolve. She remains undeterred by Maya’s rebuffs, maintaining an innocent faith that someday she will find proof that cannot be denied.

Over the course of the series, Kozue’s fundamental nature does not undergo a dramatic transformation, but her experiences do reinforce and refine her interests. A turning point occurs in the episode centered on her, when her willingness to risk her life to touch the occult culminates in a near‑death experience that briefly traps her spirit outside her body. The ordeal does not dim her enthusiasm; instead, it seems to confirm for her that the unseen world is real, even if its dangers are genuine. She continues to chase after the unexplained, though perhaps with a slightly sharper awareness that not all mysteries are harmless.

In terms of abilities, Kozue does not possess any supernatural powers or combat skills. Her true contribution is an extensive, if sometimes uncritical, knowledge of occult lore and a sixth sense for detecting the strange. She is a walking repository of urban legends, esoteric theories, and pseudo‑archaeological speculation. This makes her occasionally useful when the group needs to identify a ritual or a cryptic symbol. More than anything, her value lies in her unwavering belief and her talent for stumbling into the kinds of phenomena that the academy’s more methodical investigators might otherwise overlook.