Saka no Ue no Mahoutsukai

The sorcerer Rii and his apprentice Raberu reside in the hills on the outskirts of Geru, a town where many sorcerers dwell. Between Rii steering clear of the town and his eccentricities, it may not be the most interesting home life, but Raberu fills his days by going to school and learning about magic. But who is Rii, the strict and kind sorcerer, and why is he watching over Raberu?