Witch on the Holy Night

It is the late 1980s. Rumors of a witch living inside an old mansion circulate in the city. Unbeknownst to observers, living inside the mansion is an actual witch, Alice Kuonji, a stoic woman and a magus hiding in the present day. Under her tutelage studies Aoko Aozaki, a high school student studying magecraft as the head of the Aozaki family. As magi, the two of them secretly fight any threat that enters their town.

Things start to change when a young man unfamiliar with city life, Soujuurou Shizuki, enters their lives. Slowly, he affects the lives of these two magi. And so their story begins...

(Source: TV Tropes)