Mami Nagase takes on the erotic infidelity of a lustful gal wife presented by the new Dramax Kiwami!! Yuta comes to Tokyo to attend a university there, but soon after he starts living alone, his apartment suffers a water outage and he ends up living with his older brother and his wife in Tokyo. Asami, his older brother's wife, is interested in her young brother-in-law Yuta, and gradually begins to seduce him!! His infidelity escalates as he is seduced by the sex appeal of his big-breasted gal sister-in-law, and he writhes his hips lasciviously and moans wildly during his infidelity with his brother-in-law!!