Ten years after their mother's passing, the two sisters, Natsumi and Kozué, began living with her stepfather, Motonori Mizuno. At first, Mizuno was kind to them, but his attachment to the two grew day by day, surpassing mere restraint and bordering on domination. The 35-year-old elder sister, Natsumi, and the 30-year-old younger sister, Kozué, had given up on a normal life. Their only solace was finding pleasure in their intimate relationship as sisters. What awaits them at the end of this unbridled pleasure, is it dependence or atonement...?
