Homeroom teacher of Kunugigaoka Junior High School, Class 3-E. Possesses Mach 20 speed and power capable of destroying 70% of the moon. Normal weapons cannot leave a single scratch on him, but special weapons made of anti-teacher material (knives and BBs, which are harmless like rubber to humans) can harm him. He can regenerate in seconds even if partially destroyed, but his movements slow down as physical damage accumulates. Catchphrases: "It would be nice if you could kill me," and laughs like "Nurufufufu" or "Nyurufufufu." When surprised, he cries out "Nyua!" He loves sweets.

Keeps notes on Koro-sensei's characteristics and weaknesses. Has light blue hair styled in twin tails. Small build, standing at 159cm. Androgynous appearance; sometimes forced to cross-dress. Oblivious to the feelings Kayano has for him. Karasuma notes he has a natural talent for assassination. He even possesses kissing techniques taught directly by Bitch-sensei.

A handsome boy with red hair and a tall stature. Frank and aloof, he speaks in a provocative, mocking manner. Calculating and strong in a fight. Furthermore, he is the best in Class 3-E at the "basics" of using weapons and surprise attacks. He was the first student to deal damage to Koro-sensei. He is often with Nagisa, but there is a slight, indefinable distance between them.

Green hair styled in two-side-up tails. Has a cheerful personality and is a cute-type girl. Has a complex about her chest size. Loves pudding.

Has a moody and fickle personality. Gyaru-style long hair with aggressive-looking eyes. Often goes with Karma to tease Nagisa (sometimes bordering on sexual harassment). Excellent at English.

A boy with hair covering his eyes. According to him, it helps him aim by blocking out unnecessary information. No one in the class has ever seen his eyes. Ranked first among the boys in marksmanship, with a significant lead over the second-place Isogai. Karasuma evaluates him as a sniper with no equal in long-range shooting and spatial calculation. Not a very assertive personality; he's the professional type who lets his results speak for him. Often seen with Hayami.

Orange semi-long hair and blue eyes. A dry, unassertive professional. A cool beauty and a tsundere. Often seen with Chiba. Karasuma describes her as a "soldier with a great balance of hand precision and dynamic visual acuity, excellent at picking off moving targets." A professional who speaks through results.

Pink hair and blue eyes. Short for Autonomously Intelligent Fixed Artillery. A new weapon equipped with advanced AI. Appearance is a black rectangular slab fixed to the floor. There is an LCD monitor on the front where her face is displayed. Often jumps into people's smartphones as "Mobile Ritsu."

Dispatched from the Ministry of Defense's Special Forces as a physical education teacher and assassination instructor. Serious, hardworking, and stoic—a very rigid personality. Incredibly strong.

Irina Jelavić. A professional hitwoman dispatched as an English teacher. Has a curvaceous, glamorous body. Surprisingly shy and inexperienced when it comes to her own actual romance.