Because their father died early and their mother remarried someone else, sisters Miru and Shion have a new family. Miru is the older sister and is a lively, intelligent and pure schoolgirl. Shion is the younger sister, she is quiet and somewhat dislikes her new father. Some time later, their mother became pregnant. The stepfather took both mothers to their maternal home to facilitate the birth. Since mom is not at home. The stepfather always used lewd eyes to look at both sisters. And the first person he attacked was Shion. Taking advantage of Shion's low self-esteem when compared to her sister, he quickly manipulated her emotions, making her listen to his every word. Miru found out and to save Shion, she volunteered to be his replacement. But the feeling of happiness that her stepfather brought made her gradually lose herself. Both sisters were gradually brainwashed by him, unable to live without his cock...