After causing a costly car accident, Seiji is forced into a secret sexual arrangement with Yukino, the wife of the car's owner, to settle his massive debt. However, the situation takes a dark turn when the owner, Tomioka, orchestrates a sinister plot to kidnap Seiji's partner, Ai, and her sister, Kokoro. Seiji is left devastated as he discovers the women have been coerced into a life of debauchery, becoming playthings for Tomioka and his associates.
While recovering in the hospital, Seiji's relationship with his devoted girlfriend, Ai, is jeopardized by the appearance of his ex-girlfriend, Shouko, a nurse at the facility. Shouko uses blackmail and drugs to manipulate Seiji, eventually orchestrating a sadistic plot to force Ai into a traumatic encounter with her and an accomplice. Seiji is forced to witness the horror as Ai is drugged and violated, leaving both of them emotionally shattered.
To pay off debts incurred by Sei-chan's accident, Ai secretly takes a job at an adult entertainment club. When Tsutomu, Sei-chan's senior, discovers her secret, he manipulates her into a sexual relationship. After comparing Tsutomu's physical prowess to Sei-chan's, Ai's perception of her partner shifts, leading her to the heartbreaking decision that she can no longer visit him.