The hentai is based on the popular manga "Seikatsu Shuukan" by Michiking. Since this is a tankobon collection, it is not yet known which specific story will be adapted or what order of adaptation will be used when releasing the hentai. 

 

Shuntaro - the main character of this story, was not much different from a typical Japanese otaku, having no girlfriend and spending all his free time on eroge simulators. The only thing that distinguished him from the crowd of gloomy hikikomori was the presence of three younger sisters. The girls wholeheartedly hated their perverted brother, who used their panties instead of tissues during masturbation. Shuntaro, after another beating from his "loving" sisters, fulfilled his dreams of an older sister with the help of computer games. One day, his fantasies became reality. But not in the usual for hentai way, when a sexual beast literally falls on the hero's head from the monitor screen. He simply woke up in the morning, being 10 years younger, becoming the happy owner of a whole THREE older sisters. Pretending to be a friend of Shuntara (himself), he began to fulfill his sexual fantasies. @aleks_saotome