Yuka married Shikihiko, the father of her stepson Kazuhiko, and they built a life together as a family of three. But when her husband suddenly died in an accident, Yuka was left alone with Kazuhiko. Unable to accept his father's death, Kazuhiko rejected Yuka as his new mother, lashing out at her and even assaulting her as a way to escape reality. Eventually, Kazuhiko's secret reaches his classmate Sanada, who offers to tell Yuka the truth. Desperate to keep his secret hidden, Kazuhiko pleads with Sanada—but the notorious troublemaker smirks and taunts him: "Then how about lending me your mom too?" The atmosphere turns instantly tense as a new wave of trouble begins to unfold.