The central theme of Gakuen Heaven follows Oshino Makoto on his journey to become a teacher, driven by his desire to keep a promise he once made to his childhood friend and first love, Koiwai Ayano. The two vowed to marry if they ever met again, but Makoto falls short of realizing his dream and instead finds himself as a substitute teacher at a prestigious all-girls private school managed by his grandmother. This new job exposes him to a host of female students, including the prominent Narusawa Tsugumi and a teacher named Asagiri Ayano, who bears a striking resemblance to his lost love. In addition, his cousin Kyouko, who serves as the acting principal, sets her romantic sights on him as well.
