In the year 20XX, a law legalizing rape was passed in parliament as a measure against declining birth rates. This abnormal law stipulated that forced impregnation would no longer be considered a criminal act. On the morning the law took effect, nurse Mairi Mori headed to work, struggling with fear and anxiety. The patient under her care began acting strangely, and she would soon be betrayed by colleagues she once trusted. With the enforcement of the OK Law, rape rapidly spreads throughout the hospital, giving rise to a new wave of terror.