Toya serves as a Shikabane member of the antagonistic Shichisei group. Her headless form is covered by a coat, topped instead by a cluster of balloons.

Her core ability manipulates minds through these balloons. By attaching one to a person, she amplifies their happiness to a lethal peak. This power acts as a curse, stemming from her perception of death as ultimate happiness. She employed this curse on a student named Nozomi, binding her to a fatal happiness-inducing balloon. During this event, Toya ensnared Makina Hoshimura within an illusory amusement park, reinforcing her equation of death with joy.

Toya originated from a poor family. Her parents took her to an amusement park for a final day of enjoyment before a planned family suicide; they poisoned her soda there. This trauma cemented her distorted worldview, associating death with happiness while remaining unaware of her own undead state.

Her character arc concludes when she questions her own concept of happiness, causing her primary balloon to burst and triggering a monstrous transformation. Kanechika Umehara terminated her following this transformation. Her demise occurred shortly after another Shichisei member, Hizuchi, recounted her tragic backstory and intervened in a confrontation involving Makina and Nozomi.