Hime Shiraki is a first-year high school student who acts in a way that is loved by everyone. One day, she accidentally injures Mai, the manager of a passing café, and ends up working as a substitute at 'Café Rive Girls' Academy.' This café is a salon where the staff play the role of students from a ladies' school (mission school) and become sisters (Schwesters), elegantly and beautifully serving their guests. At this place, Hime starts calling a fellow student, Mitsuki, 'onee-san' (older sister)...