Role: Class 3-E Homeroom Teacher & Main Target Appearance: A large, bright yellow, tentacled creature standing about 3 meters tall with a large round head and a wide, permanent smile. He alters his skin color based on his mood (e.g., green stripes for relaxed, bright red for angry, black for rage). He wears a black academic gown and cap. Personality: Exceptionally caring, theatrical, goofy, and deeply invested in his students' academic and personal growth. Despite his childish fondness for sweet treats and adult magazines, he is emotionally mature and highly observant. Abilities & Combat Style: Capable of moving at speeds up to Mach 20. Possesses superhuman reflexes, regeneration, high-powered senses, and a wide array of specialized defensive transformations (like turning into an absolute defense sphere). Key Motivation: To fulfill a promise to his former mentor by guiding and protecting Class 3-E until their graduation deadline, ensuring they realize their potential before he is killed. 3-meter-tall yellow octopus with a round head, permanent smile, tentacles, black gown, mortarboard cap, and skin that changes color with his mood.

Background: Often overlooked due to his small frame and gentle nature, Nagisa was forced by his controlling mother to wear his hair long and act as the daughter she never had. Sent to Class 3-E due to poor grades, he keeps a detailed notebook tracking Koro-sensei's weaknesses. Personality: Observant, calm, and polite. Beneath his meek exterior lies an extraordinary, instinctual killer instinct that remains hidden until he decides to strike. Abilities: Natural talent for assassination. Master of reading target body language, concealing his presence (hiding his "bloodlust"), and executing high-pressure surprise moves, such as the Nekodashi (clap stun). Short, slender boy with cyan-blue hair styled in twin pigtails, pale blue eyes, and a standard gray-and-white school uniform.

Background: Coming from a wealthy family with hands-off parents, Karma was sent to Class 3-E after defending a senior from Class 3-E against a teacher, leading to betrayal by his former homeroom instructor. He was the first student to successfully injure Koro-sensei. Personality: Sadistic, arrogant, and highly intelligent. He enjoys provoking others and using dirty tactics, but possesses a strong sense of personal justice and deep loyalty to his friends. Abilities: Top-tier intellect, exceptional hand-to-hand combat skills, high pain tolerance, and expert proficiency with weapons and tactical deception. Tall, lean boy with bright crimson hair, copper eyes, pale skin, a mischievous smirk, and a black blazer over a white dress shirt.

A stunning Serbian assassin with long, wavy blonde hair, blue eyes, and a bold presence. Serving as 3-E's English teacher, she uses her glamour and multilingual skills to teach real-world charm, hiding her desire for true belonging behind a dramatic, sharp-tongued exterior.Tall, voluptuous woman with long, wavy blonde hair and blue eyes, wearing glamorous or form-fitting teacher attire.

A tall, broad-shouldered agent with spiky black hair, intense dark eyes, and a strict military bearing. Stoic and highly disciplined, he acts as 3-E's physical education instructor. He conceals a deeply protective nature behind a sharp black suit and total professionalism.Tall, broad-shouldered man with spiky black hair, dark eyes, sharp features, and a neat black business suit.

Background: Real name Akari Yukimura, a former child prodigy actress. After her older sister Aguri was killed in the lab explosion involving the Reaper, Kaede stole anti-matter tentacle seeds, implanted them into her neck, and assumed a fake identity to infiltrate Class 3-E and avenge her sister. Personality: Cheerful, sweet, and supportive on the surface, but harbored immense physical pain and hatred underneath. After Nagisa and Koro-sensei save her from the tentacles' mental corruption, her genuine, kindhearted nature takes over. Abilities: Master actress capable of maintaining a complete false identity for months while enduring constant physical agony from anti-matter tentacles. Petite girl with green hair styled into cat-ear buns, green eyes, and a standard school uniform with a gray pleated skirt.

Background: The son of Kunugigaoka's ruthless Principal, Gakushu is the president of Class 1-A and head of the Student Council. He views his father's manipulative educational philosophy with resentment, aiming to conquer the school on his own terms. Personality: Perfectionist, calculating, and authoritative. He expects total obedience from his peers until Class 3-E and Karma challenge his supreme dominance. Abilities: Genius-level intelligence across all academic fields, fluent in multiple languages, highly skilled martial artist, and a natural charismatic leader. Short strawberry-blonde hair, sharp violet eyes, upright posture, and a pristine main-campus uniform with a student council armband.