Ayane Sato manifests solely to those nearing death, visible only during firework displays at a particular abandoned airfield. She appears as a young woman with auburn hair and brown eyes, presenting a composed figure rather than a spectral horror. Her death followed a heated argument with her mother, after which she fled into a storm and was struck by a vehicle. The panicked driver concealed her body in a suitcase and buried it, trapping her spirit in unresolved trauma. She wandered the physical world, seeking her remains to grant her mother closure. Ayane’s existence embodies profound loneliness and regret; she asserts death offers no freedom, only isolation, contrasting it with life’s unrealized potential for change, travel, and romance.

She interacts primarily with teenagers Tomoya, Aoi, and Ryō, acting as a catalyst for their growth. Ayane challenges Tomoya’s view of death as an escape from family pressures, urging him to value life and pursue aspirations. Her statement—"I’m not bothered by ghosts, but I am bothered by people who can’t be honest with themselves"—prompts self-reflection. Her hidden body and unresolved fate drive the group’s quest, particularly Tomoya’s shift from despair to proactive resolve.

Ayane’s narrative concludes when her remains surface in a landfill, freeing her spirit. Returning her brooch to her mother delivers emotional closure. This resolution empowers the living: Tomoya confronts his mother about his artistic ambitions, and Aoi faces her bullies. Thematically, Ayane signifies existence’s fleeting nature, with fireworks metaphorizing life’s vibrant yet transient possibilities. Her story underscores mortality’s finality, ending all chances for connection and growth.