From the introduction:
Welcome to the world of Angel Academy, an h-doujin series by Katsurai Yoshiaki. In this world’s Japan there exists a prestigious boarding school for young ladies, the titular Angel Academy, where wealthy families send their daughters to be brought up in isolation from the public, and especially from men. Angel Academy is an escalator school which raises these girls from grade school all the way through college, all without ever exposing them to any noteworthy interaction with the opposite sex. After all, these young ladies are only any good for marrying off to wealthy and influential men, or so the thinking goes with these old-fashioned bluebloods, so they must be kept pure and refined into worthy brides for their eventual husbands.