Based on the adult game by Moonstone Cherry. <br> <br> Keiichi lives under the same roof as his five younger sisters and he had a problem… he couldn’t help but be turned on by his sisters developing bodies.<br> <br> One summer vacation, their parents decided to go on an overseas trip, leaving Keiichi home alone with his sisters. Ririna, his serious younger sister, took a strict attitude toward Keiichi, thinking that her sloppy and perverted brother would become more and more vulgar while her parents were away.<br> However, Ririna secretly masturbates, even while saying that she hates naughty things.<br> And Keiichi just so happened to know that...<br> <br> (Source: Getchu, translated)