An older sister who is about to get married and her still-virgin younger brother take a bath together for the first time in over a decade. "I will never feel anything for my sister's breasts," he boasts. However, when they are washing each other with soap, his sister pulls back his foreskin, causing him to instantly become erect and revealing his virginity. Despite having a fiancé, the older sister's libido is awakened by her brother's large penis, and they celebrate with incestuous sex and ejaculation, marking his first time. NGHJ-059.