Sayuri Sasaki is an office lady working at a credit company. She has been in a long-term relationship with her boyfriend, with whom she lives together, and they are planning to marry next spring. However, they have sex only once or twice a month, and the routine has become stale, leaving her increasingly unsatisfied. Emotionally unfulfilled by her current partner, she now suffers from chronic sexual frustration. Her 28-year-old body, once awakened through vibrators, restraints, and intense stimulation by a former lover, craves the passion missing in her current relationship. Tormented by persistent desire, this lustful office lady decides to explore a new path to fulfillment through an affair, just before officially registering their marriage.