Mr. Rotter believes in order and has little patience for students that try to cause chaos. He is, however, not a strict teacher and enjoys to spark enthusiasm for both his classes and the other ones in the students. This means that sometimes Rotter fails to understand when students are not enthusiastic about some of the classes. He is known for never giving 'A's.
He has quite a high opinion of himself. He claims he was Hexiciah Steam's favourite student, however the man himself told Rotter that he was his 'least' favourite student.
Rotter has grey-to-green skin and sandy hair. He is usually dressed in a brown coat.
- December 16, 2010: Rotter makes his 2D cartoon debut in "Idol Threat".
- February 12, 2012: Rotter makes his 3D cartoon debut in "Why Do Ghouls Fall in Love?".
- Late May, 2013: Rotter makes his diary debut in Lagoona's 13 Wishes diary.
- Rotter is designed after Lon Chaney's 1925 iteration of the Phantom of the Opera, though the Phantom is a separate character.