Guest's much older brother. He dotes on Guest and is overprotective, despite his stern demeanor. Naberius Kalego. A very strict teacher at the demon school, Babyls. Homeroom teacher for the Abnormal Class. His catchphrase is "Silence." He is weak against Sullivan.

Balam Shichiro. A teacher at Babyls. Teaches Imaginary Biology. He was classmates with Kalego and they are close friends. Due to his rugged appearance and long hair, students rumor he performs human experiments. However, he is kind and loves living things. He knows Guest. He spoils her rotten whenever they meet.

Dantalion Dali. Male. A teacher at Babyls. Head of the faculty. He is always smiling. He loves interesting things. He loves playing along with pranks. He is a veteran who has been at Babyls for a long time. Teaches Demon History. He does not know Guest.

Murmur Tsumuru. Male. A teacher at Babyls. Teaches Psychology. The voice of reason. His tone becomes blunt and rude when talking to his colleagues. He does not know Guest.

Ipos Icho. Male. A teacher at Babyls. Teaches Tactics. He looks serious but is actually very willing to join in on pranks. His tone becomes blunt when talking to his colleagues. He does not know Guest.

Ifrit Jin Eight. Male. A teacher at Babyls. Head of Security. The voice of reason. Gentle with students. His tone becomes blunt when talking to his colleagues. He does not know Guest.

The Chair-Demon of Babyls and one of the "Three Heroes," the high-ranking demons closest to being the next Demon King. The one who brought Iruma to the Netherworld. He dotes on his first grandson, Iruma, while warmly watching over his growth. He knows Guest. He spoils her rotten as if she were another grandchild.