Packaged with the seventh volume of the Shinmai Maou no Testament manga, this OVA delves into Maria's unique idea of birthday celebrations. With a mischievous plan in mind, she orchestrates a scenario to bring Mio and Basara closer together by using a birthday pretext and a touch of forbidden magic. Amidst the guise of celebration, Maria aims to set the stage for a steamy and unforgettable encounter.