Marginal Prince: Gekkeiju no Ouji-tachi is based on the popular love simulation game series for girls. The story follows Yuuta, who travels abroad to the remote Pacific island of Alphonso to study at the all‑male, all‑dormitory Alphonso Gakuen. In reality, the school is reserved for the children of prominent families and specializes in courses on empire-building and alchemy. After completing their studies, the students earn the title of “Marginal Prince.” The series chronicles each student’s stories of fate and trial as they strive to become future kings.