Yuka marries a man with an adult son, Kazuhiko, but her husband dies in an accident and leaves the two alone together. Unable to accept his father's death or the sudden presence of a stepmother, Kazuhiko escapes reality by assaulting her. Their twisted life continues until his adult classmate Sanada discovers the secret. When Kazuhiko begs him to stay quiet, the cruel young man demands a price: “Then let me borrow your mom too,” opening the door to endless group abuse.