Mr. Dubby

Mr. Dubby (더비, Dubby) is Satan, Sheryn, and Beelzebub's homeroom teacher.

Appearance
Mr. Dubby's usual appearance is that of a large mass of goo.

In rare instances, Dubby can transform into a more humanoid form. His humanoid form has grey hair, a goatee, a light grey checkered vest with dark long sleeved dress shirt, and ribbon bow tie.

Trivia

 * Mr. Dubby first met Satan, his future student, when Satan was hitching a ride with his mailman to school.