you's homeroom teacher.
The assassination target of Class 3-E. He teaches all subjects except English conversation and P.E. He is an unidentified creature with a round face and many tentacles, resembling a yellow octopus. He usually wears a grinning expression. His laugh is "Nurufufufu," and when he is flustered or surprised, he lets out a peculiar cry: "Nyuya!"

A classmate.
A boy with a light blue hairstyle resembling pigtails. He is a self-proclaimed and widely acknowledged extreme herbivore, and is basically quiet, gentle, and good-natured. Through the process of cornering and attempting to assassinate Koro-sensei, he has honed his observational skills and is constantly taking notes on Koro-sensei's traits and weaknesses.

Class 3-E.
A red-haired boy with a frank personality and an easygoing attitude. He is frank and nonchalant, and speaks in a way that seems to mock people.
He is also calculating and quite strong in a fight, and when it comes to the "basics" of weapons and surprise attacks, he stands out even within Class E. He was the first student to deal damage to Koro-sensei.

Class 3-E.
A cheerful and beautiful girl who personally gave the Class E homeroom teacher the nickname "Koro-sensei." She sits next to Nagisa, so they have a good relationship. She is flat-chested.
She is the only girl whom Nagisa calls by her first name without an honorific. She likes pudding.

Class 3-E. A female student with long black hair and a neat, refined air. She is a beautiful girl characterized by her gentle smile. She is considered the foremost madonna of Class E and ranks first among the boys' "ranking of girls they're curious about in class," but she is also very popular among students of the same gender.

Class 3-E. A female student with a ponytail hairstyle.
She has a reserved personality and doesn't assert herself, but in addition to her good nature, she has an E-cup bust and a good figure among the girls in the class, so she ranks second in the boys' "ranking of girls they're curious about in class." She is learning techniques from Irina.

Class 3-E. A male student characterized by his ahoge, and he serves as a class representative for Class E together with Kataoka. He is a versatile honor student who acts as a leader for Class E, and his courage and dynamic vision are among the best in the class. He ranks first among the boys in knife skills and second in shooting.

A female student with bright-colored hair and an innocent, cheerful personality. Because of her unprejudiced demeanor and cute features, she ranks third in the boys' "ranking of girls they're curious about in class."

A female student characterized by her wavy semi-long hair and eyelashes. She has a good balance of manual dexterity and dynamic vision, excels at taking down moving targets, and ranks first in shooting among the girls in Class E.
She is usually quiet, rarely shows her emotions, and has a strong core that doesn't make excuses. She loves cats.

A male Self-Defense Force officer belonging to the Ministry of Defense's Temporary Special Task Force, and the P.E. teacher.
A young man with a rigid personality that combines seriousness, dedication to work, and asceticism.
The nickname given to him by the class is, naturally, "stick-in-the-mud."
He is the person who brought Koro-sensei to Class E as their homeroom teacher.
He monitors Koro-sensei, coordinates between Class E and the assassins, and provides backup. He is the very person who invited you in.