Rie, who lost her husband in a car accident three years ago, lives with her non-biological son, Yuma. Yuma finds himself increasingly captivated by his young and sexy stepmother. Meanwhile, Rie has remained chaste for these three years and has been living through days of sexual frustration. One day, Saki, the wife of Yuma's brother Haruma who died in the same accident, visits, and their relationship begins to move in an unexpected direction...