Saella is a famous songstress and taught humans how to use songs as a magic. Saella locked herself with the magic Crystal in order to protect it from dark magic users. Saella was losing hope on magic, but after watching over Guy and the MC she decided to free herself from the Crystal and to give magic another chance. She starts teaching on Gedonelune as a temporary professor and plans to open her own school in another world. In Glenn’s route, Saella was imprisoned in the crystal until Glenn managed to release her through the use of magic. Because of the feelings shared between Glenn and the MC, and their good intentions, she forgives them for releasing her. With help, she releases The Place Where Time Has Stopped from being frozen in time. She was the fourth official professor to teach in Gedonelune.

I imagine her with an elegant and soothing voice. However your own takes on her are alright as well!