Aoi Nagisa transfers to a new Catholic girls only school and discovers a community of fellow students entwined in an intricate heirarchy, at the top of which sits the all important Etoile. In order to fit in, Nagisa must go to class, join clubs, and make new friends. Meanwhile, Shizuna Hanazono, the Etoile of the school, finds herself drawn to this new, exciting transfer student. As Shizuna and Nagisa get to know eachother, Shizuna finally decides it is time to face her troubled past.

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.