Although Koiji is still passionately in love with his wife, Chisato, he has recently been frustrated by his inability to get an erection. Desperate not to be abandoned by Chisato, Koiji resolves to use an aphrodisiac. However, while Koiji is away, Chisato and their son accidentally drink a beverage laced with the aphrodisiac. Their vaginas begin to throb even without being touched, and their penises stand tall. Overwhelmed by the sudden heat coursing through their bodies, the two gradually step into a forbidden relationship.
