Takashi accidentally witnesses his best friend Satoshi's mother, Reiko, in the midst of an affair, trembling in shock. Overwhelmed by the sight of Reiko—the woman he's secretly admired—engaging in such lewd and explicit behavior, he's consumed by a complex mix of lust and jealousy. In a split-second decision, he begins covertly recording the scene, capturing his racing emotions on audio. The next day, learning that Satoshi is away, Takashi visits Reiko's home. Confronting her with the evidence of her infidelity, he presses her—only to find himself drawn into an unexpected turn of events.