The protagonist, Houkou Hayao decides to take a job interview at a family resto, Berry's, in order finds out what to do when he graduates.
On the same day as the interview, he bumps into a certain "ojou" who just got out from the interview room in a bad mood, and binge eats at Berry's. He later ended up hanging around with her. When he gets home, he finds out that Yuuka, his "imouto," has found out that he got a job without her permission.
Later, he learns that the binge-eating girl which introduces herself as Morikubo Yuna he met is a new employee like him.
