Yuki causes a traffic accident while driving, resulting in the death of her senior, Kozue, who was a passenger. Accompanied by her father, Yuki offers an apology... Kozue's father, Kamikawa, sets a condition for the compensation: "Become the adopted daughter of the Kamikawa family in place of my deceased daughter." It was an utterly unacceptable condition, but Kamikawa also agreed to take on the enormous debts of Yuki's father, forcing the adoption through. As the daughter of the Kamikawa family, Yuki is disciplined from scratch. Kamikawa takes advantage of Yuki's failures to tighten his control and gradually commit acts of abuse...