Magical Witch Concerto

There is a magic school located on a southern island, where female students learn magic hard every day. Fran, Chloe, and Nathalia.... They are going to graduate from school next year, but they haven't mastered how to call a familiar spirit. Their grades aren't bad, but they somehow can't call it. One day, they decide to call a familiar spirit together, but it fails again.... When they are disappointed, they find a naked boy lying in front of them. "Who is he...?" It's Rio. He seems to have been called by the girls.... He, who doesn't remember the things before he is called, starts living with the girls.... Who will Rio make a contract with? Where is Rio from? Their busy and H school life now begins...!