A full century has passed since magic was accepted as a functional technology, and it's now April 2095. The highly esteemed National Magic University Affiliated First High School, also known as "Magic High School," has just welcomed two new students who happen to be siblings. Tatsuya, the eldest, has a rare and disabling defect in his magical skills, whereas his younger sister Miyuki is unrivaled in her magical potential. Although their bond has become so close that it is often mistaken for romance, there was once a strained relationship between the siblings, with Tatsuya serving as the master and Miyuki as the servant. However, their dynamic changed irrevocably three years prior during a life-altering incident in Okinawa that altered their paths and destinies.