Staying over at his friend Tetsuya's house, Okada becomes captivated by his beautiful and mysterious mother, Mio. That night, Okada heads to the kitchen for a drink of water and stumbles upon Mio pleasuring herself while on the phone. Her lewd actions are beyond imagination, instantly arousing Okada. Unwilling to let this chance slip away, Okada blackmails Mio by threatening to expose her secret unless she submits her body to him—only for events to spiral into something far more intense than he ever anticipated.