Eighteen years ago, Masako divorced her husband and has since lived alone with her son. As her son reached adulthood, he graduated from a national university and joined the sales department of a major beer company. Three years into his job, he began facing the harsh realities of working life. Desperate to succeed and earn his mother's approval, he pushed himself hard, yet saw no results. Through this struggle, his attachment to Masako twisted into something abnormal. Gradually, he became consumed by forbidden feelings, falling for her not as a mother—but as a woman.