Married for 15 years, Maki finds herself trapped in a monotonous daily routine, growing increasingly lonely. As her intimacy with her husband fades, she begins questioning the meaning of her life. One day, she meets Ikeda, her husband's subordinate, and gradually becomes involved in a romantic affair with him. Despite feeling guilty toward her husband, Maki is swept away by the pleasure of sex after so long, becoming emotionally dependent on Ikeda. The thrilling passion and excitement of this new life—so different from her ordinary existence—begin to shake her soul.