Kohane Tsuyuri is a young medium whose life changes dramatically when her spiritual powers bring her into the public eye as a child television star on paranormal programs. Her ability to see and sense supernatural presences comes at a young age and has a profound effect on her family circumstances. When she used her powers to help her mother uncover her father's infidelity, the revelation shattered her mother's mental state, causing her to become cold, controlling, and emotionally abusive. Her mother stopped touching her, refused to speak her name, removed any objects or food she considered impure from the home, and began forcing Kohane into constant television appearances to capitalize on her fame, leaving the family surrounded by material wealth but lacking genuine warmth. This deeply isolating upbringing causes Kohane to develop a quiet, composed, and remarkably mature personality for her age, and she often takes the blame for her family's unhappiness upon herself.

Her primary motivation is a selfless desire to make her mother happy again, and it is this wish that she eventually brings to the witch Yūko Ichihara. Kohane's role in the story is that of a significant supporting figure whose arrival deepens the narrative's themes of inevitable connections and the price of wishes. She forms a particularly strong bond with the protagonist, Kimihiro Watanuki. Recognizing a shared loneliness and sensitivity to the supernatural, Watanuki becomes the first person to show her genuine kindness and to call her by her given name. In return, she develops a deep affection for him and becomes the only person who calls him Kimihiro-kun, showing her unique closeness to him.

The relationship with Yūko Ichihara becomes the turning point in her life. In exchange for her wish, Kohane offers her entire spiritual power. Yūko accepts the payment but only takes the external source of her purification ability, a powerful feather connected to another reality, rather than her natural gift for seeing spirits. Yūko also resolves the negative rumors surrounding Kohane in the media and arranges for her to live with a kindly fortune teller, who becomes a maternal guardian and teaches her the trade. This new living situation allows Kohane to leave her toxic home environment, attend a regular school, and grow up in a healthier setting. Over time, she forges a steady connection with Shizuka Dōmeki, and in the later timeline of the series they become engaged, showing how deeply she has integrated into the central circle of characters.

Kohane experiences significant personal development over the course of the series. She transitions from a passive, lonely child who endures harsh treatment without complaint into a young woman with a stronger will, capable of protecting those she cares about. She demonstrates this hidden strength when she firmly confronts her mother for hurting Watanuki, declaring that harming someone she loves is unforgivable. Her growth is symbolized by her cutting her hair, a quiet act of reclaiming her identity and moving forward into a new chapter of her life.

Regarding her abilities, Kohane possesses an innate and remarkably strong power to see spirits and sense malicious auras. This is a natural talent that remains with her. She also briefly possessed the power of spiritual purification and exorcism, but this was not her original gift; it was granted by an external magical artifact not meant for her world. After Yūko removes this artifact as payment for her wish, Kohane retains her natural mediumship. In her later life with the fortune teller, she learns the art of fortune telling, putting her sensitivity to spirits to practical use in a way that is entirely her own.