The Amamiya couple enjoys a happy marriage and a harmonious home life. Every day, wife Kotone sees her husband off to work with a smile. One day, a charismatic female insurance saleswoman named Hibiki Otsuki visits her. Kotone politely declines the insurance pitch, as her husband is already covered. But Hibiki tempts her with a free gift, drawing her in with seductive charm and persuasive words. Using a vibrator included in the promotional gift, Hibiki skillfully seduces Kotone, captivating her body and mind. This fleeting encounter will drastically change Kotone's everyday life forever.