Based on the erotic game by Zero.<br> <br> Shiori and Saori are twins, and they have a secret crush on the "oniichan" that lives next door. Recently they developed an interest in H. "I'll have "oniichan" teach me various things."<br> <br> When summer comes he is asked to look after the house and the girls by their mother. Since its summer vacation there is a lot of free time. How fun can house sitting become?<br>