Great Tree Eniyunien

Great Tree Eniyunien is the spirit born from the rumors and legends of the "Great Tree of Learning". He also acts as the Spirit School itself.

Ennunien has the voice of a hoarse old man, but is very calm and composed. As a teacher, he gets very excited when a student asks a question. However, he is very sensitive about his teaching and gets angry after the class criticizes his bad drawings.

(Source: Maou Gakuin Wiki)