A Level 0 (powerless) boy attending high school in Academy City's District 7. He possesses a mysterious power in his right hand called 'Imagine Breaker,' which negates all supernatural abilities, whether psychic or magical. 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 is a person who risks his life to save those in danger. To his homeroom teacher, Komoe-sensei, he is a troublesome student who is always dragged off to remedial classes for failing, but he deeply trusts and follows her as she truly worries for him.

A classmate and close friend of Kamijou Touma and Tsuchimikado Motoharu, forming the so-called 'Failing Trio.' Standing over 180cm tall, he is characterized by his delinquent appearance, featuring flashy dyed blue hair and various piercings on his face. Despite his looks, he has a cheerful and friendly personality, speaks in a Kansai dialect, and serves as the class mood maker. He is a hardcore otaku who is enthusiastic about all sorts of moe attributes like maids, lolis, and big sisters; he occasionally gets scolded by Touma for having self-indulgent delusions about their teacher, Komoe-sensei. While he usually appears as a lighthearted gag character, he is a mysterious individual who sometimes gives off an air 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 'Failing Trio.' He is characterized by his flashy Hawaiian shirts, constant sunglasses, and a unique way of speaking, ending his sentences with "-nya." He usually acts like a foolish gag character, but he hides a massive secret: he is a magician belonging to the British Puritan organization Necessarius and a multi-spy for Academy City (member of the underground organization 'Group'). Formerly a genius magician of the Onmyouji lineage, he became a Level 0 after undergoing esper development in Academy City, and now faces the risk of his body breaking down whenever he uses magic. He is a severe siscon who dotes on his non-blood-related younger sister, Maika, and acts as a secret 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 certain high school in District 7 and is Kamijou Touma's homeroom teacher. Despite her petite, 135cm elementary-schooler appearance, she possesses a striking gap in personality, chain-smoking and chugging 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. While she constantly nags Touma, a troublemaker who fails habitually, she genuinely worries for him and makes sure he attends remedial classes. 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 is a reliable ally who uses her expertise and connections to provide subtle yet decisive help in resolving various incidents.

An expressionless, taciturn girl with long straight hair and a shrine maiden-like aura who transferred into 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 timid and kind-hearted beautiful girl with glasses and a large bust 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 accumulation of AIM diffusion fields emitted by the espers of Academy City. Since her essence is an energy body, she risks vanishing if touched by Touma's right hand, but she tries her best to protect Touma and the friends who treat her as a person.

A strong-willed and responsible class leader who leads the Level 0 failures of Academy City. She punishes troublemaking boys with her signature headbutt.