The action of hentai takes place in our time somewhere in Tokyo. The main characters of the twins Shiori and Saori have long been in love with their “big brother”, who lives next door to them. With the onset of summer vacation, the twins ‘ mother asks him to look after their home and sisters, since he has a lot of free time. Of course, lustful Shiori has long been making plans for the summer and the move of her brother was a great opportunity for her and Saori to have a great time and learn all sorts of different things…