Yumi Hashiba is an 18-year-old Japanese female with brown hair and ochre eyes, standing 157 cm tall with a slender frame. She lives with her older brother, Yuuto Hashiba. Their close relationship is complicated by mutually harbored, unspoken romantic desires for each other. Neither sibling had acted on these feelings before encountering a mysterious VHS tape.

Yumi discovers the same magical VHS tape Yuuto previously viewed. This tape reveals the viewer's deepest hidden fantasies. When Yumi watches it, the tape unlocks her own repressed desires involving Yuuto, confirming their mutual attraction. The tape specifically manifests vivid BDSM scenarios depicting Yuuto dominating her.

Viewing the tape triggers an intense, unresolvable lust within Yumi that conventional methods cannot satisfy. This experience propels her into subsequent events where she and her female friend become subservient to Yuuto's desires. The tape's curse actively reshapes their reality, forging a master-slave relationship dynamic.