“I know it’s for my sister’s sake, but... Is it really all right to lie to a girl and sleep in the same room as her?!” 16-year-old shut-in Yoruhiko's twin sister, Akane, ends up in a coma after getting into an accident. Not wanting to ruin her perfect attendance, Yoruhiko decides to continue her record by going to school in her place. But, in order to do so, he must disguise himself as her and attend an all-girls boarding school! How will former recluse Yoruhiko keep up his act when surrounded by his sister's friends and roommate?