Nagisa Aoi is a first year high school student who has been sent to the Astraea Dormitory after her parents are transferred abroad. The dormitory houses girls from three different girls' schools: St. Spica's Academy, St. Le Rim Girls School and St. Miatre Girls Academy. There she meets the representative of the three girls' schools, Shizuma Hanazano, also know as the Etoile, who is beloved by all students at all schools. The two of them have an interesting first encounter and Hanazano seems to take an instant liking for Aoi.