Possesses a remarkably mature appearance for Academy City, where youth predominates. Consequently, her voice sounds like that of an adult woman. However, she was likely a high school student until at least a year ago (based on her "class representative" line in Dark Side Coexistence Vol. 3), placing her around 18 to 19 years old. (Though Mikoto called her an old lady...) Her personality is self-centered and arrogant. She shows no mercy to enemies and can be extremely violent, even turning on allies if her pride or precious things are harmed. However, her "deep affection for comrades" is a double-edged sword that leads to a fixation where "betrayal is absolutely unforgivable." This, combined with Teitoku Kakine wounding her pride, likely led to her atrocities in Old Testament Vol. 15. According to Rikou Takitsubo, she is "single-minded once she sets her heart on something." She often adds "Nyaan" to the end of her sentences, but combined with her rough tone, it's more terrifying than cute. Frenda leaked her unexpected secret that she "can't sleep without hugging a tattered stuffed animal." She is self-conscious about her legs being thick, so she always wears stockings, tights, or knee-high socks to make them look thinner. Her favorite food is salmon bento; she surprisingly prefers Japanese cuisine. Ability: Meltdowner (Atomic Destruction), Level 5, Ranked 4th.

A member of 'ITEM,' an organization active in the dark side of Academy City. Her catchphrases are "Ultimately..." and "...is the point." She is proud of her beautiful legs and is a high school student. Level 0. Her specific ability is unknown. Her personality is frivolous and optimistic, approaching everything with a lighthearted attitude. This is a strength that allows her to easily bond with others and clear their worries, but it also manifests as a bad habit of underestimating dark side work (including target elimination) and quickly resorting to self-preservation. She also possesses a sadistic streak, finding pleasure in tormenting targets and feeling as if she controls their destiny at the moment she takes their life. She can enjoy watching others kill each other while eating popcorn and watches the rule-free underground 'Coliseum' live streams while having meals in her room.

A member of 'ITEM' who is always seen in a tracksuit. She is secretly well-endowed. While organizations formed by ability users often consist of members with cold-hearted ideologies, she is a healing presence amidst the bleakness. Her personality is quiet and kind. However, as a member of the dark side, she is hardly a "good person" and does not stop Mugino or Frenda when they massacre or torture targets in front of her. At best, she is loyal and caring toward her comrades; at worst, she is indifferent to herself and others. Shiage Hamazura, who became ITEM's errand boy, was saved to some extent by her kindness. She entered the dark side after scientists framed her to use her in 'Body Crystal' experiments. She was saved by Mugino during that time and has cherished her comrades ever since. According to Saiai, she is a high school student. Ability: AIM Stalker (Ability Tracking), Level 4.

An ability user belonging to 'ITEM.' Level 4 'Offense Armor.' A quiet-looking girl who appears to be about 12 years old (though she claims to be a middle schooler), wearing a fluffy knit dress. The dress is extremely short, but she calculates the angles so nothing is actually exposed. Her verbal tic is adding "Super-" to everything. Since it's used as a prefix, she can use it multiple times in a single sentence. In her private life, she is a fan of B-grade movies or worse (and her hobby is collecting used tickets from movies she's seen). Even for R-rated films, she will use a fake ID to visit empty theaters. She has specific preferences for how to watch movies but gets bored easily. Ability: Offense Armor (Nitrogen Armor), Level 4.

A character from "A Certain Magical Index" and one of the protagonists of the series. Level 0. Height is about 175cm. As a Level 0, he has no noteworthy combat abilities but primarily fights using weapons. He is skilled at handling guns and driving cars. Additionally, he acquired minor technical skills and knowledge such as forging IDs and dismantling ATMs during his time in Skill-Out. His lock-picking skills are particularly impressive, having successfully picked the precision analog lock of a Dragon Rider in one go. Rikou tends to be a bit jealous, and Shiage is dissatisfied when their time together decreases. Despite everything, the two are deeply in love.