Today YuMe's parents traveled, her sister took this opportunity to invite her boyfriend to play. YuMe was doing the essay, so she asked her boyfriend - Tsukasa to help. Tsukasa used to steal Yume's underwear and she discovered it. So if Tsukasa didn't want her to talk to her sister, he had to agree to do it with her. And from there the two people compressed each other, private rooms, bathrooms, kitchen, ... even when a sister was near ...