Cygnus Maidens: The Irregular at Magic High School

The novels are set one year after Tatsuya and Miyuki graduate, and center on two girls named Arisa and Marika. Though raised as sisters, Arisa is one day entrusted to the elite Jumonji magical family, separating them for two years. Now, both are enrolled at First High School, and finally reunite.

(Source: Anime News Network)