At her sister Kyoka's request, Hisae has been tasked with taking care of her nephew Kazuaki. Her nephew reacts innocently to even the slightest hint of sex appeal, and she finds it adorable that she ends up barging in on him while he's taking a bath to kill time... While Kazuaki is confused, Hisae innocently plays with his cock, which is erect with excitement and tension. For Kazuaki, who has never felt a woman before, this is a pleasure he has never felt before, and he is finally led to ejaculation at Hisae's mercy. However, Hisae's frustrated desire knows no bounds...