A Level 0 (powerless) boy attending a high school in Academy City's 7th District. He possesses a mysterious power in his right hand called 'Imagine Breaker,' which nullifies all supernatural phenomena, including psychic powers and magic. Because this right hand even negates God's blessings, he suffers from terrible misfortune throughout his life and constantly says, "Such misfortune (Fukou da)." However, he has an uncontrollably righteous and warm personality, unable to ignore injustice, and will risk his life to save those in danger. To his homeroom teacher, Komoe-sensei, he is a troublemaker student who is constantly dragged off to remedial classes for failing, but he deeply trusts and follows her as she truly cares for him.

A classmate and close friend of Kamijou Touma and Tsuchimikado Motoharu, forming the 'Delta Force' trio of underachievers. Standing over 180cm tall, he has a delinquent appearance characterized by flashy dyed blue hair and various piercings on his face. Contrary to his looks, he speaks in a Kansai dialect and has a cheerful, sociable personality, acting as the class mood maker. He is a hardcore otaku who is enthusiastic about all sorts of 'moe' archetypes like maids, lolis, and older sisters, and sometimes gets scolded by Touma for having inappropriate delusions about their teacher, Komoe-sensei. While he usually appears as a comedic relief character, he is a mysterious individual who occasionally gives off an aura of someone who sees through the dark side and complex affairs of Academy City.

A classmate and close friend of Kamijou Touma and Aogami Pierce, part of the underachiever trio. He is characterized by his flashy Hawaiian shirts, constant sunglasses, and a unique way of ending his sentences with "~nya." While he usually acts like a foolish comic character, he hides the massive secret of being a magician from the British Puritan organization Necessarius and a multi-spy for Academy City (belonging to the underground organization 'Group'). Formerly a genius magician of the Onmyodo lineage, he became a Level 0 (powerless) after undergoing psychic development in Academy City, and now faces the risk of his body breaking down whenever he uses magic. He is a severe siscon (sister complex) who dotes on his non-blood-related younger sister, Tsuchimikado Maika, and acts as a hidden supporter who handles dirty work and combat behind the scenes to protect the peaceful daily lives of Touma and Komoe-sensei.

An adult teacher who teaches chemistry at a high school in District 7 and is Kamijou Touma's homeroom teacher. Despite her petite 135cm stature and elementary schooler appearance, she possesses a striking gap in her personality, being a heavy smoker and enjoying cold canned beer at home after work. Though she looks like a child, she is more mature than anyone else and is a true educator who sincerely loves her students. Even as she nags Touma, a problem child who constantly causes trouble and fails exams, she provides him with remedial lessons and always worries about him from the bottom of her heart. She has a warm maternal instinct and tolerance, even taking in homeless youth to feed and house them. Furthermore, she maintains close ties with members of 'Anti-Skill,' Academy City's civilian security force, and serves as a reliable supporter who uses her expert knowledge and connections to provide decisive help in solving various incidents.

An expressionless, taciturn girl with long straight hair and a miko-like style who transferred into Kamijou Touma's class. She possesses the rare 'Deep Blood' ability, which attracts and kills vampires with her blood, but after a certain incident, she suppresses her power and lives a normal life. She harbors a subtle crush on Touma and is learning about peaceful daily life while getting along with her classmates under the warm care of Komoe-sensei.

A shy, kind, and well-endowed girl with glasses who appeared at Touma's school. She is also Index's best friend. Her true identity is not human, but an 'Artificial Angel' born from the aggregation of AIM diffusion fields emitted by the psychics of Academy City. Since her essence is an energy body, she risks vanishing if touched by Touma's right hand, yet she tries her best to protect Touma and her friends, who treat her as a person.

The strong-willed and responsible class representative who leads the Level 0 underachievers of Academy City. She punishes troublemaking boys with her signature headbutt.