Kisa Tanigawa is the female protagonist of the winter story arc set in Yokohama. She is a high school girl who has withdrawn from the world around her, having stopped attending school and choosing to keep most people at a distance. Her days are spent wandering the city, often walking to watch the boats come in, passing the time without a clear sense of purpose or direction. This behavior stems from a deep-seated belief that she is not needed by anyone and a fundamental inability to accept herself.

One evening, her isolated routine is broken when she witnesses small spheres of light fighting near a bridge. She follows them and later finds a wounded fairy of light in a street corner, taking it home with her. She names the creature Bun-chan for the soft sound it makes, and this encounter acts as a catalyst for change in her life. The fairy’s presence begins to draw Kisa out of her shell, sparking a journey of friendship and self-discovery.

Kisa’s personal story is deeply intertwined with a small circle of people. Her most significant relationship is with Rieko Yamato, a friend who spends her days caring for Kisa despite the latter’s withdrawn nature. The delicate balance of their friendship is also affected by Masaki Makabe, who harbors feelings for Rieko, and Shigeki Kobayakawa, a young man intensely focused on becoming a professional shogi player. As Kisa becomes involved with the fairy and the mysterious phenomena occurring in Yokohama, the dynamics between these four individuals begin to shift.

Throughout the narrative, Kisa undergoes notable development, moving from a state of listless isolation to a more engaged and self-aware individual. Her initial passivity, defined by wandering and waiting for the day to end, is gradually challenged by her connection to Bun-chan and the strange events unfolding around her. She does not possess any overt superpowers or special combat abilities. Her role in the story is not defined by physical strength but by her emotional journey and her interactions with the fairies of light, which are central to the themes of the series.