Adult son Yuto cannot accept his mother Yuka's remarriage. After spending so many years alone with her, he has come to see her as more than family. When he witnesses Yuka having sex with his new stepfather, Yuto is consumed by jealousy. Heartbroken by her adult son's hunger for love, Yuka gently guides him as both a mother and a woman. Though they know their relationship is forbidden, the two sink into lust that crosses the boundary between mother and son...