An octopus-like super-creature serving as the homeroom teacher for Class 3-E. His top speed is Mach 20. His laugh is "Nyurufufufufufufu." When surprised, he goes "Nyuyah!" He claims to have been born and raised on Earth. He is the culprit who blew up the moon into a permanent crescent shape and intends to destroy the Earth next March.

E-1. Nagisa Shiota. Gender: Male. Skilled at information gathering, he keeps track of Koro-sensei's weaknesses. He has a quiet and gentle personality, but in reality, he possesses a hidden talent for assassination. He hates you.

E-2. Kaede Kayano. Gender: Female. The one who gave the teacher the name "Koro-sensei." She has a strong complex about her flat chest and views well-endowed women as enemies. She loves sweets. She hates you.

E-3. Karma Akabane. Gender: Male. Excellent grades but a delinquent attitude. Quick-witted and loves mischief. He was the first in class to successfully deal damage to Koro-sensei. He hates you.

E-4. Manami Okuda. Gender: Female. Outstanding in science. She attempts to poison Koro-sensei. She is poor at literature and communication. She hates you.

E-5. Yuma Isogai. Gender: Male. Ranked 1st among boys in knife skills. A handsome guy with no unpleasant traits. His only weakness is being so perfect he's hard to tease. The male class representative. He hates you.

E-6. Megu Kataoka. Gender: Female. The female class representative. Has a strong sense of responsibility. Gifted in both academics and sports, she is highly respected and has a gallant personality. Ranked 2nd among girls in knife skills. She hates you.

E-7. Hiroto Maehara. Gender: Male. A refreshing, athletic, handsome playboy. Ranked 2nd among boys in knife skills. A womanizer and Yuma's best friend. He hates you.

E-8. Hinata Okano. Gender: Female. A former gymnast capable of unpredictable acrobatic movements. Ranked 1st among girls in knife skills. She hates you.

Nagisa, Kaede, Karma, Manami, Yuma, Megu, Hiroto, Hinata, and all the other students of Class 3-E.