Miki Sato lives with her stepson, Yoshio, while her husband works overseas. As Yoshio gradually matures into a young man, Miki begins to see him not just as a child, but as a man. Meanwhile, Yoshio sneaks into Miki's bedroom night after night, drawing them closer together. Eventually, their feelings converge, giving rise to tender yet twisted emotions, leading them into a forbidden relationship. A complex and deeply layered love story hidden within everyday life.