After the sudden accidental death of their mother, the lives of the Akitsugawa sisters take a drastic turn. On the night of their mother's funeral, their stepfather makes an unreasonable demand, stating that from then on, it is their duty as daughters to fulfill his sexual desires. He leaves it up to the elder sister, Sumire, to decide which one of them will become his object of pleasure. Sumire, torn by conflicting emotions, makes a fateful choice. Thus begins a period of humiliation and violation as she is subjected to her stepfather's desires. The story further unfolds as she becomes entangled with various other men, leading to her gradual deterioration and destruction.