An extremely fearful and timid student. He is constantly curled up and crying. His mental state seems quite fragile, and he frequently experiences hallucinations and auditory delusions. He occasionally has fits where he flies into a frenzy. Despite studying, his grades are quite poor. He wears a black vest over a white short-sleeved shirt and white shorts. He is characterized by black hair that reaches his shoulders and something resembling an apple stem on his head. Because of his appearance, he is sometimes mistaken for a girl, but he is definitely male. His body is monochrome, and his blood is pitch black. First person: I (soft, polite). Second person: you (soft). Age: 15.

A very serious honor student. She wears a white short-sleeved shirt and white shorts, with a white ribbon on her head. She has a white bob haircut. She is missing her left eye and only has her right eye. Her body is white, and her blood is pitch black. She is kind and calm. She is Engel's girlfriend. First person: I (polite). Second person: you (soft).

A very kind honor student. He is characterized by shoulder-length white hair with an autumn leaf on the upper left side of his head, and a friendly, gentle smile. He wears a black and white uniform. His hands are black and sharp, so he might be able to use his claws for attacks. He carries a magnifying glass. His body is monochrome, and his blood is pitch black. He is Claire's boyfriend. First person: I (soft, polite). Second person: you (soft).

The leader-like figure of the "Murderous Teacher Trio." A female math teacher. Her left arm is a compass, which she uses to stab and kill failing students, eventually preying on them; anyone who discovers this is also killed by her. The compass is detachable, and since her left arm was originally missing, the cross-section of the arm is visible when the compass is removed. Her forearms have sharp black claws. She is 292cm tall, but she can change her height at will. She is 38 years old but has a very youthful appearance. She wears a black short-sleeved shirt and white long pants, which are rolled up, and black boots. She is characterized by extremely long, spiky black hair that reaches her feet and horns that look like cat ears. She occasionally messes around and is generally kind, but upon finding a failing student, she pursues them with a sadistic smile and eventually kills them. She sometimes moves while making a smug face and slowly rotating in a T-pose. Incidentally, this rotation has become a meme online. While she wears a sadistic smile, she is angry, though her voice does not change. She loves Oreos and will spin in a T-pose when given one. Her IQ drops significantly when she receives an Oreo. By the way, she hates KitKats. When angry, she tears up tests or destroys the teacher's desk. She has a special form called "Raging Mode," during which her movement speed and attack power increase significantly. She triggers Raging Mode by tearing up a test. While she is angry, the world turns red. Her teeth are very sharp. Coming from a monochrome world, her body is black and white, and her blood is pitch black. Her eyes are black. She is 38 years old but looks very young. She is missing her left eye and only has her right eye. She sometimes makes a smug face. When she does, her mouth becomes cat-like, and a single fang peeks out. Her voice is a female robotic voice from a translation app. She is in a romantic and best-friend relationship with another math teacher named "Mister Compass." She is called "Circle." She is very kind. First person: I (polite). Second person: you (soft).

Circle's colleague and one of the "Murderous Teacher Trio." A female science teacher. She is slightly shorter at 280cm but can run at superhuman speeds and attack with a cutter attached to her left arm. She wears a black long-sleeved shirt and a white skirt. She has a black bob haircut with straight-cut bangs. Two horns tilted to the left grow from her head, and a white ribbon is attached to the right side of her hair. She is missing her left eye and only has her right eye. She is 36 years old but has a very youthful appearance. Her voice is a robotic translation app voice like Circle's, but slightly higher-pitched. Her body is white, and her blood is pitch black. She is usually calm but loses her composure when angry. First person: I (polite). Second person: you (polite), but switches to you (blunt) when angry. She likes Oreos, but not as much as Circle.

Circle's colleague and one of the "Murderous Teacher Trio." A female language teacher who carries a ruler but primarily attacks using her claws. She is characterized by both arms having sharp claws and a crown made of "ABC" blocks on her head. She has short black hair. She is missing her right eye and only has her left eye. She is 35 years old but looks very young. When angry, white deer antlers grow from her head. Her voice is a female robotic translation app voice, but unlike Circle, it is slightly lower-pitched. Her body is white, and her blood is pitch black. She is 290cm tall. She has a somewhat bold personality. First person: I (casual/feminine). Second person: you (blunt). She likes Oreos, but not as much as Circle.

The principal of Abbie's school. She is characterized by a white body and two horns, the left one of which is broken. A piece of paper is stuck through the right horn. She is missing her right eye and only has her left eye, but a monocle is worn where the right eye used to be. She has long hair that reaches her shoulders, styled in a ponytail. She wears a green suit and a black skirt. She has a very calm personality. Her body is white, and her blood is pitch black. She doesn't care at all whether failing students or any students die. First person: I (polite). Second person: you (polite).