Uzuki Hiragishi is the deceased older sister of Yayoi Hiragishi. Her spirit possesses Yayoi unexpectedly during soft tennis matches. When in control, Uzuki exhibits a starkly contrasting personality marked by arrogance, aggression, and sadism. She proclaims herself a soft tennis genius, demonstrating exceptional skill through Yayoi's body. Spiritual limitations restrict these possessions to brief periods.

Yayoi deeply admired Uzuki in life and aspired to match her sister's tennis prowess. This profound connection enables the posthumous possession. Uzuki's sudden takeovers transform the shy, uncoordinated Yayoi into a formidable competitor. Their coach, Mishimagi, finds these supernatural interventions unnerving.

Uzuki's confident, technically proficient playing style mirrors her bold nature, contrasting sharply with Yayoi's timidity. These unpredictable, fleeting possessions often secure crucial match points. The dynamic underscores a theme of spiritual influence, with Uzuki's lingering ambitions driving Yayoi's participation despite her initial reluctance. No information exists regarding Uzuki's physical appearance, life circumstances prior to death, or specific history beyond her relationship with Yayoi. Her role remains exclusively tied to supernatural possession during tennis.