Atsuko Ueno, age 45. One day, she discovers her son with an erection while still wearing her lingerie. His penis clearly visible through the lace fabric. As a mother, her pride and concern grow intensely, but her son promises it will never happen again. Yet, as time passes, the same situation occurs once more. Though troubled by her son's behavior, she struggles with what she should do. She worries endlessly about why he developed this strange habit and how she can possibly correct it.