Etsuko, a 41-year-old married woman with three children and 17 years of marriage behind her, has only ever known her first lover—the man she married—and has never been with another man. Her husband tells her, "I want you to be with other men and become even more beautiful," encouraging her to cheat. Surprised by his words yet sensing the fleeting nature of her own time, Etsuko begins to feel curiosity toward other men. Embarking on an affair with her husband's permission, she's torn by conflicting emotions but gradually surrenders to pleasure, swaying in hot spring waters as her heart and body tremble—invited into a journey of passion as a married woman.