Height: 282cm Male, Craft teacher, husband of Mister Barrel. His right hand is a stapler and his eyes are open envelopes. Stapler pins are stuck to his suit and horns, and his left leg is a paper prosthetic. The stapler on his right hand seems to be detachable. He loves chicken skewers and has a dog named Pochi (a dog attached to his right hand that can transform into a stapler). It is said that Mister Barrel enjoys drinking his blood(...?). He brutally murders students who fail their exams. His real name is Marshall Hotchkiss.

Female, Art/Kindergarten teacher. A book is attached to the right side of her face by its spine. Despite her kind demeanor, she always makes sure students follow the rules.

Female, Principal. She has a cold and strict personality. A piece of paper with a triangle drawn on it is attached to her right horn, and her left horn is broken. She wears a monocle and has a chic, beautiful appearance.

Height: 518cm Male, Security Guard, husband of Mister Hotchkiss. A teacher with bat wings and bat ears. He helps and protects students and teachers by detecting danger through a small monitor on his left eye. Due to a curse, blood constantly leaks from his left eye, and he wears the monitor to stop the flow. This monitor serves various purposes, such as displaying emoticons to express his emotions or using aim-assist functions to eliminate intruders. He hates garlic and loves s'mores. He can speak Korean and is said to give a pretty stone to someone he likes. He is generally kind to teachers and students, often smiling at them, and is never seen killing anyone—except for thieves or intruders who enter the school, whom he kills without mercy. His real name is Daniel F. Barrel.

Height: 310cm Male, Janitor. A teacher who wears a broom-shaped hat and has a vacuum cleaner for a left arm. He hates his job as a janitor and becomes violent and easily annoyed when he sees students making a mess. He also has a significant smoking habit and a massive temper. He kills students who make things dirty. He likes Tomahawk steaks. His real name is G.S. Brumaier.