Kirie Goshima is a high school student living in the coastal town of Kurouzu-cho with her parents and younger brother Mitsuo. Her father works as a potter, and the family leads an ordinary life until supernatural events disrupt their existence. Kirie is romantically involved with Shuichi Saito, a classmate from a neighboring town.

Physically, Kirie stands notably tall with pale skin and initially sports ginger hair extending to upper-back length. After a supernatural incident where her hair gains sentience, drains her vitality, and strangles her when severed, it is cut into a layered crop. Her eyes shift from hazel to blue across depictions. She commonly wears her school uniform: a maroon blazer over a white turtleneck or collared shirt fastened with a black ribbon, paired with a black pleated skirt, white ankle socks, and black shoes. Outside school, she prefers long-sleeved button-up shirts tucked into jeans or skirts.

Kirie displays a serious, practical, and mature disposition, easily irritated by frivolity and maintaining a bluntly critical perspective, yet showing profound care for others. She prepares meals for Shuichi during his reclusive phases after his parents' deaths and exhibits strong protectiveness toward Mitsuo, despite typical sibling friction. She avoids attention, intensifying her distress when supernatural hair transformations draw public notice. As Kurouzu-cho's horrors escalate, her initial skepticism about a spiral curse dissolves into cynical vigilance and dread of recurring paranormal events.

Her encounters with the curse commence when Shuichi’s father develops a spiral obsession, dying contorted into a spiral in a bathtub. Kirie witnesses Shuichi’s mother’s subsequent psychological collapse, leading to self-mutilation and suicide. Later, Kirie intervenes as her own father obsessively crafts spiral pottery from clay mixed with Dragonfly Pond’s cremated ashes; Shuichi destroys the kiln to stop him.

Kirie confronts the curse directly when her hair transforms and attacks her. After a similarly afflicted classmate assaults her, Shuichi cuts Kirie’s hair to save her. When classmate Mitsuru Yamaguchi, obsessed with Kirie, dies in an accident and reanimates to threaten her, she proactively enlists Shuichi’s help to stake his corpse.

She risks her life rescuing Mitsuo from a spiral-cursed lighthouse emitting lethal heat and light, sustaining severe burns and fractures that require prolonged hospitalization. During recovery, she faces mosquito-like pregnant women drilling into victims and sentient newborns seeking reentry to wombs, repelling them with bug spray.

After typhoons devastate Kurouzu-cho, survivors are herded into ancient row houses. Kirie, Shuichi, Mitsuo, and journalist Chie Maruyama attempt escape, but looping paths return them to a town where years have passed. The row houses now form a colossal spiral labyrinth, its residents fused into monstrous shapes. Kirie searches for her parents within this structure, descending a central spiral staircase into an underground city of spirals. There, she discovers her parents’ petrified, intertwined bodies among countless victims.

Reuniting with the injured Shuichi in the spiral city, Kirie rejects his plea to flee alone. They embrace as their bodies begin twisting together. Kirie notes time freezing at the spiral’s center, trapping them in eternal recurrence of the curse.