The mother and her two little children were having a prosperous and happy life until both children were adults, everything was disturbed. The beautiful older sister Inoue and her younger brother are both grown-ups, especially the older sister who has had a successful puberty: the big round breasts and plump buttocks make the younger brother more and more superb, and sometimes some dark thoughts come to his mind. The older sister is becoming more and more mature, caring for her mother and brother attentively. It all started to happen on the day when she had a high libido, she didn't know what to do, so she had to masturbate to satisfy her needs, unfortunately being found out by her younger brother. Like an adult woman, the next day she dared to flirt with her brother because after so many years together, she also knew that he had noticed her for a long time. And so the incest between them progressed more and more in hiding the mother.