Academy City is introduced as a metropolis where the majority of the student population possesses supernatural abilities, known as espers, which are ranked by level. The episode establishes Mikoto Misaka as one of only seven Level 5 espers in the city, earning her the title of "The Railgun". Her roommate, Kuroko Shirai, is a Level 4 teleporter who serves in Judgment, a student-run law enforcement organization. Following their system scans, which measure esper abilities, Kuroko arranges for her Judgment colleague Kazari Uiharu and Uiharu's friend Ruiko Saten to meet Mikoto. Saten initially expects Mikoto to be arrogant due to her high rank but discovers she is friendly and unassuming. The four girls spend time together at a crepe stand, where Saten notices Mikoto's interest in a limited-edition Gekota frog mascot and gives her the last one. Their outing is interrupted when Uiharu observes a bank with its security shutters closed during business hours, moments before an explosion occurs. Three masked robbers, one of whom is a pyrokinetic esper, flee the scene. Kuroko immediately intervenes, using her teleportation ability to disarm and subdue two of the criminals. During the chaos, a young child from a tour group goes missing, and Saten locates him near the street, only to be kicked by the third robber as he attempts to take the boy hostage. Witnessing Saten's injury prompts Mikoto to act. As the remaining robber flees in a car and drives directly toward her, Mikoto uses her electromaster ability to launch a metal arcade coin like a railgun, destroying the vehicle and ending the threat. The captured pyrokineticist realizes he is facing the Level 5 esper known as the Railgun. Afterward, Anti-Skill, the adult security force, arrives to take the robbers into custody. A portable audio player is visible in the pyrokineticist's pocket as he is led away. Saten reflects on the day's events, recognizing the heroic actions of her new acquaintances.

The episode opens with Misaka chasing a spiky-haired boy through the city, only for her Electromaster abilities to be completely nullified by his right hand, leaving her confused and the area behind him oddly unscathed. The narrative then shifts to a slice-of-life setting in the Tokiwadai dormitory, where Misaka's friends, Saten and Uiharu, visit her room for the first time. Kuroko, Misaka's roommate, has meticulously planned what she considers a one-month anniversary celebration with Misaka, but her romantic aspirations are thwarted by the presence of their friends. The conflict arises from Kuroko's obsessive feelings for Misaka clashing with Misaka's desire for a normal social interaction with her new friends, leading to a series of comedic yet revealing exchanges. The tension escalates when Kuroko's true intentions are exposed through a delivered package of aphrodisiacs, prompting a fierce but brief esper duel between her teleportation and Misaka's electricity. A major turning point occurs when the Dorm Supervisor intervenes, strictly enforcing the rule against using powers inside the dormitory and punishing both girls with the task of cleaning the school's swimming pool. The immediate consequence of their clash is the physical labor of cleaning the pool, a setting that forces them into a temporary truce. While working, Kuroko's classmates from the swim team arrive, and their conversation inadvertently highlights Misaka's protective nature, as one girl thanks her for intervening against thugs. The episode concludes with the girls still at their task, underscoring that while their abilities make them powerful, they are still subject to the rules and mundane responsibilities of student life. The opening scene with the mysterious boy who can negate her powers remains an unresolved plot thread, hinting at a larger conflict beyond the daily lives of the students.

Saten accompanies Uiharu to the School Garden to meet Misaka and Shirai, but an accident with a puddle leaves her uniform soaked. She borrows a Tokiwadai Middle School gym uniform, which inadvertently makes her a target for a series of assaults occurring in the district. Shirai and Uiharu are called away to their Judgment duties, where they learn from their supervisor Konori that several Tokiwadai students have been attacked with a stun gun and had their faces marked with ink. The victims reported being unable to see their attacker, suggesting the use of an ability that conceals the perpetrator's presence. While alone in the cafe restroom, Saten is struck by the same invisible assailant. Misaka discovers her unconscious friend and brings her to the Judgment office. Saten regains consciousness and, upon viewing a database, identifies the culprit as a girl with a distinctive hairstyle whose reflection she glimpsed in a mirror before being attacked. The group uses the city's extensive surveillance network, with Uiharu hacking the feed to track the suspect's movements. Misaka and Shirai pursue the girl, eventually cornering her in a park where Misaka neutralizes her with an electrical attack. The culprit, a Level 2 esper named Harumi Kiyama, confesses that her motivation stemmed from romantic rejection by a boy who preferred a Tokiwadai student. She explains that her ability, Dummy Check, allows her to appear invisible by shifting others' attention away from her, which functioned beyond its registered level during the attacks. Saten, upon seeing Kiyama's naturally thick eyebrows, states that she finds them appealing, a moment of unexpected empathy before Anti-Skill arrives to take the culprit into custody. The resolution of the immediate case leaves an underlying question regarding how an esper's power could manifest with a strength exceeding their official Level 2 designation.

The episode follows Misaka and her friends as they investigate various urban legends circulating within Academy City. Saten, motivated by her status as a Level 0, shows particular enthusiasm for collecting stories about supernatural phenomena and rare abilities. The group examines rumors including a fortune-telling ability that allegedly allows one to steal another person's luck. Misaka approaches these tales with skepticism, viewing them as baseless speculation rather than factual occurrences. The investigation leads the characters to different locations throughout the city, including a brief encounter with a fortune teller who provides a cryptic reading for Saten. Kuroko remains focused on her duties with Judgment, providing a contrast to the recreational nature of the urban legend hunt. The episode establishes a connection between the urban legends and the broader narrative arc when Misako learns about rumors concerning students collapsing after experiencing level ups. This information plants the first seeds of concern regarding the Level Upper phenomenon that will drive future conflicts. Saten's growing interest in these rumors foreshadows her later decisions regarding ability enhancement. The episode balances character interactions with plot development, showing the daily lives of the protagonists while introducing elements that will become significant. The immediate consequence of the episode is the establishment of a mystery that prompts continued investigation by the main characters.

The episode centers on a conflict between Judgment members Kuroko Shirai and Kazari Uiharu. During a routine patrol, they witness a theft. Kuroko disregards Uiharu's advice to wait for backup, teleporting into an ambush that allows the thieves to escape and injures Uiharu. Frustrated, Uiharu confronts Kuroko about her recklessness and is further upset when Kuroko appears to have forgotten a significant promise from their past. The narrative then shifts to a flashback detailing the origins of their partnership. Some time ago, Kuroko and her senior, Mii Konori, responded to a bank robbery. Kuroko's impulsive actions escalated the situation, resulting in a young Uiharu, who was merely a bystander, being taken hostage. The robber, an esper, used an ability that injured Konori when she shielded Kuroko from another rash attack. Recognizing the consequences of her behavior, Kuroko used her teleportation to move Uiharu to safety outside the bank. She then chose to confront the remaining robber alone, accepting responsibility for the events she had set in motion. Her stand was ultimately successful due to the anonymous intervention of Mikoto Misaka, whom Uiharu had begged for help. Following this traumatic event, Kuroko and Uiharu made a shared promise to remain true to themselves and to become full-fledged Judgment members together. Back in the present, Kuroko finally remembers this promise. She apologizes to Uiharu, and they reconcile. Working in unison, they track down and apprehend the car thieves they had encountered earlier, demonstrating the trust they rebuilt from their shared history.

Following Kongou's injury, the episode divides its focus between two concurrent battles. Wannai and Awatsuki engage Yoshio Baba directly to prevent his escape and to retrieve a mosquito drone he implanted in Kongou. Baba deploys robotic Great Dane drones to attack the two students, relying on his analysis of their abilities. Wannai uses her Hydro Hand ability to manipulate water from a nearby reservoir, while Awatsuki employs her Float Dial power to alter the gravity of objects. Baba exploits Wannai's apparent limit of controlling three water streams simultaneously, forcing her to exhaust her supply by destroying his robots. However, Wannai reveals she had secretly guided a fourth stream through a storm sewer, which she uses to envelop Baba's head. Panicking, Baba orders his remaining drones to absorb the water, which causes them to short-circuit. Awatsuki neutralizes his final mosquito drone, and the pair retrieve the intact device for analysis. Meanwhile, at a hospital, Saten explains the situation to Mikoto, who sees the severely injured Kongou on a stretcher. Mikoto detects an electronic signal from another mosquito drone hidden in Kongou's hair and confiscates it. Driven by anger, she leaves the hospital and uses the drone's homing signal to track Baba to his surveillance van. Before she arrives, Baba releases a large mantis-style robot, mistaking Mikoto for one of the Sisters. Mikoto effortlessly destroys the machine and, using its communication system, announces her presence. Finding himself locked inside his van due to Mikoto's electromagnetic control, Baba is confronted by her. Mikoto warns him to cease his actions but spares him due to uncertainty about his connection to the girl controlling the Sisters. The episode concludes with the skull-pendant girl, dressed in purple, receiving a report of Baba's failure. She resolves to handle the situation personally, despite a warning from her brown-haired companion about Mikoto's capabilities.

The episode advances the graviton bomber storyline as Kuroko and Konori deduce that Judgment officers themselves are the intended targets, not incidental victims. This realization shifts the investigation's focus and creates immediate urgency when a new bombing signature is detected at the Seventh Mist shopping center where Uiharu is located. Concurrently, Saten's subplot develops through her conversation with Mikoto, where she expresses feelings of inadequacy about lacking esper powers and mentions the urban legend of the Level Upper. Her laughter after these remarks does not fully conceal her underlying frustration about being unable to contribute like her friends. The shopping trip provides a temporary diversion until the bombing threat forces an evacuation. A little girl approaches Uiharu with a stuffed toy frog, delivered on behalf of a man with glasses, which begins to exhibit graviton collapse. Uiharu throws the toy away and shields the child. Mikoto attempts to destroy the bomb with her railgun but drops her arcade token, preventing the shot. The explosion occurs, yet no one is injured. Following the incident, Mikoto locates and confronts the culprit, a bullied boy named Kaitabi who has been using his growing powers to attack Judgment out of resentment for their failure to protect him. He attempts another attack but is subdued when Mikoto vaporizes his weapon. Kuroko informs him that Mikoto herself rose from Level 1 to Level 5 through effort, and that she would have stopped him regardless of her power level. The episode concludes with Mikoto privately acknowledging to Kamijou that his intervention, not hers, prevented casualties, though he dismisses the importance of credit.

The episode opens with Uiharu Kazari absent from school due to illness, prompting her friend Saten Ruiko to deliver medicine after classes. This personal matter provides a backdrop for the central conflict, as the friends gather in Uiharu's dorm room and discuss the ongoing investigation into the Graviton Bomber, Kaitabi Hatsuya. Misaka Mikoto and Shirai Kuroko reveal their confusion over how a supposedly Level 2 could wield power commensurate with a Level 4, which reignites their interest in the urban legend of the Level Upper. Saten confirms the rumor's persistence online and, with Uiharu's help, identifies a message board where users discuss the program. Motivated by a desire to understand the discrepancy in Kaitabi's case, Mikoto decides to investigate the Level Upper firsthand, with Kuroko accompanying her out of concern. Their investigation leads them to a restaurant where purported users of the Level Upper congregate. Mikoto, attempting to gather information through an undercover approach, feigns desperation and childishness to lower the guards of the older teenagers present. Her act is a calculated conflict, a turning point where she chooses deception over confrontation to penetrate the group. The immediate consequence of this gamble is that one of the men takes an interest in her, suggesting that the information might not be free, thereby escalating the tension of the encounter. Meanwhile, the episode reinforces Saten's internal conflict regarding her own status as a Level 0. Her conversation with the bedridden Uiharu reveals her struggle to grasp the concept of Personal Reality and her quiet, underlying hope that a tool like the Level Upper could genuinely elevate her abilities. The narrative threads converge on the existence of the Level Upper as a tangible, if mysterious, program, setting the stage for its potential link to the comatose state of Kaitabi and others. The episode establishes that the pursuit of power through artificial means carries unknown risks, as the investigation into the Level Upper shifts from a rumor to a concrete threat with real-world victims.

Mikoto and Misaki continue their pursuit of Gensei Kihara through different methods, with Misaki's team locating and attempting to apprehend him at a facility. Gensei temporarily evades capture by using a body double, a deception that becomes apparent when he is seen speaking on a phone shortly afterward. The episode reveals the name of the girl who previously abducted Uiharu and Misuzu as Mitori Kozaku, a former reform school student officially reported dead but now active in the city. Kuroko and Uiharu investigate Mitori's background at a records center, uncovering her history of terrorist actions and raising questions about who facilitated her release and for what purpose. Saten independently investigates a potential lead at an abandoned factory, encountering Touma along the way who is engaged in a scavenger hunt, placing this episode's events chronologically after a specific incident in A Certain Magical Index II. The investigation suggests Mitori may not be working directly for Gensei, introducing ambiguity about her true objectives and allegiances. Misaki exhibits an unusual level of concern while protecting her base of operations where the clone 10032 is recovering, hinting at another significant asset codenamed "Exterior" hidden there. The episode builds toward a flashback sequence in the next installment, which is titled "Clone Dolly" and appears to feature a younger Misaki with an individual closely resembling a Misaka clone.

Ruiko Saten experiences the joy of wielding an esper power for the first time, using a minor wind manipulation ability granted by the Level Upper. Her exhilaration stands in stark contrast to the ongoing investigation, as Judgment members confront a surge of out-of-control users. Kuroko Shirai single-handedly manages numerous arrests, sustaining significant bruising and exhaustion from the relentless encounters. Mikoto Misaka and Kuroko hypothesize that the Level Upper may function through synesthesia, manipulating brainwaves via auditory input. Their theory gains traction when Dr. Harumi Kiyama suggests consulting the Tree Diagram supercomputer for analysis. The episode's central conflict shifts when one of Saten's friends collapses into a coma after power use. A panicked Saten confesses her involvement to Kazari Uiharu, blaming herself for the dire situation. Uiharu delivers a fervent promise to always stand by Saten, regardless of her esper level, before rushing to her apartment. She arrives to find Saten unconscious on the floor, clutching her lucky charm, a victim of the very phenomenon they were investigating. At the hospital, a doctor reveals that all comatose patients share identical, abnormal brainwave patterns. A database search for a matching pattern yields a single, near-perfect match: Dr. Kiyama herself. In a concurrent development, Uiharu, waiting in Kiyama's office, discovers concealed research on synesthesia, leading to her capture by the doctor. With Anti-Skill mobilization underway and Kuroko injured, Mikoto decides to personally confront Kiyama, who now holds Uiharu hostage.

After being drawn into the AIM burst network, Misaka directly connects to Dr. Kiyama's consciousness and witnesses her memories. This reveals the doctor's motivation for creating the Level Upper program: she is attempting to revive her students, a class of Child Errors who have been comatose since a prior experiment. The narrative focus shifts to the out-of-control AIM burst entity that manifests from the collective unconscious of the comatose children and the Level Upper users. Misaka confronts this powerful creature, which is sustained by the network she inadvertently helped to empower. Uiharu, despite her low-level abilities, plays a crucial role by using her data manipulation skills to slow the creature's advance. The conflict escalates as the creature threatens to reach a nuclear power plant, raising the stakes for the entire city. Misaka ultimately resolves to stop the entity by using her railgun to destroy the device at its core, understanding the immense risk involved. The episode culminates with the creature's destruction and the collapse of the Level Upper network, which causes all its users, including Saten, to fall into comas. In the aftermath, Misaka and the others learn the truth about Dr. Kiyama's intentions, reframing her actions as a misguided attempt to save her students rather than simple malice.

The investigation into the Level Upper phenomenon reaches a critical juncture as Misaka Mikoto and her friends trace its origin to a website managed by an organization called Skill-Out. Concurrent with this discovery, a new and powerful esper, Kiyama Harumi, emerges as a direct threat. Kiyama, a former researcher involved in a discontinued project that altered esper brainwaves, is identified as the source of a powerful energy field known as an AIM Burst, which she utilizes to amplify her own abilities. The episode depicts the confrontation between Misaka and her companions against Kiyama, where they employ their respective powers in an effort to subdue her and halt the effects of the AIM Burst. Their combined efforts successfully weaken Kiyama, bringing the immediate conflict to a close. However, the resolution of the physical battle gives way to a more complex revelation. It becomes apparent that Kiyama's actions were not entirely autonomous; instead, she was being manipulated by a shadowy, unidentified organization. This discovery recontextualizes the preceding events, shifting the target of the investigation from a single antagonist to a larger, more obscure conspiracy within Academy City. The episode concludes with Misaka and her friends acknowledging this new layer of complexity, setting the stage for a deeper inquiry into the clandestine forces behind the Level Upper and the manipulation of Kiyama Harumi. The immediate consequence of the episode is a pivot from direct confrontation to an investigative pursuit against an unseen enemy.

Members of the Tokiwadai Middle School swim club, Awatsuki Maaya and Wannai Kinoho, recruit Misaka Mikoto and Shirai Kuroko to participate as models for a swimsuit photoshoot sponsored by a designer. The group is later joined by Uiharu Kazari, Saten Ruiko, Konori Mii, and Kongou Mitsuko for the assignment. Upon arrival at a high-tech studio, the girls select from a variety of swimsuit styles, with the interactions highlighting their distinct personalities and dynamics, including Kongou's competitive awareness of Kuroko and her ignorance of Mikoto's identity as Tokiwadai's "Ace". The photoshoot takes place in a studio equipped with advanced holographic projectors capable of simulating different environments and tactile sensations. A minor malfunction in the holographic system causes the projected scenes to cycle erratically, prompting a break in the shoot. During this intermission, the group collaborates to prepare a meal, ultimately deciding to make curry rice. Kongou Mitsuko, having boasted about her culinary skills, struggles significantly with the cooking process, revealing her complete lack of experience. She accepts assistance from the others, and the collaborative effort results in a successful meal, fostering a sense of camaraderie and marking a turning point in Kongou's previously adversarial relationships with the group. Following the conclusion of the work, Mikoto remains behind to privately try on the frilly two-piece swimsuit she had been too self-conscious to select earlier. As she steps into the studio, she inadvertently activates the display system, projecting her image onto a large outdoor monitor just as Touma Kamijou happens to be passing by, witnessing the embarrassing moment.

While Misaka and Shirai discuss how to spend their day off, Saten reports to a special workshop at a different school. The session is mandatory for students who previously used the Level Upper device. The attendees are taught by Tsukuyomi Komoe, who lectures them on the theory of developing one's Personal Reality as the foundation for esper abilities. During the lunch break, Saten encounters Jufuku Miho, a timid girl from the Level Upper support group who had been writing letters to her. Miho, grateful for Saten's previous kindness, offers to share her meal, demonstrating the continued connection between former users. The afternoon session, led by Yomikawa Aiho, consists of rigorous physical training designed to teach the students about surpassing their perceived limits. One participant, a delinquent girl previously confronted by Misaka, accuses the instructors of disguising punishment as education. Saten contradicts this claim, asserting that the attendees brought the consequences upon themselves by attempting to cheat the system. Komoe later clarifies that the workshop is not a punishment but an opportunity, explaining that having experienced a higher level of power through Level Upper gives them a tangible goal to work towards legitimately. The episode concludes with ability tests showing minor improvements for the students and Saten finding an encouraging letter from Miho in her shoe locker, which strengthens her resolve. She exits to find her friends waiting for her, having spent the day unable to decide on an activity without her.

The episode introduces a new conflict centered on a group of Level 0s known as Skill-Out. Kongou Mitsuko is attacked by members of a Skill-Out gang called Big Spider but is saved by a mysterious red-haired man with a spider tattoo on his back before she loses consciousness due to a strange headache. Konori Mii from Judgment reacts with visible recognition upon hearing the man's description and the gang's name, hinting at a personal connection. Uiharu's research reveals that Big Spider's leader is named Kurozuma Wataru and their base of operations is in Academy City's 10th District, a rundown area nicknamed 'Strange'. Misaka and Kuroko travel to the 10th District to investigate. They are confronted by local thugs but are again saved by the same red-haired man, who easily defeats the attackers after they knock away his milk. The man speaks of the district as a place for those discarded by the city's level-based system but refuses to provide information on Big Spider or Kurozuma. Later, Misaka and Kuroko track Big Spider members to their hideout and confront the man claiming to be Kurozuma. The gang activates a device called 'Capacity Down,' which emits a sound that disrupts esper abilities, leaving the two powerless and vulnerable. The red-haired man arrives and destroys the device, disabling the gang's advantage. He reveals the imposter leader to be Hebitani, exposing himself as the real Kurozuma Wataru. After he single-handedly defeats the gang members, Konori Mii arrives on the scene, and her demeanor confirms a prior acquaintance with the real Kurozuma, leaving Misaka and Kuroko surprised by the connection.

Following the confrontation on the rooftop, Konori Mii avoids her duties at the Judgment office, prompting concern from her colleagues. Misaka Mikoto, Shirai Kuroko, Saten Ruiko, and Uiharu Kazari visit Konori's dormitory to investigate, where they meet her roommate, Aomi. Aomi reveals that Konori was once a member of the Skill-Out gang Big Spider during a difficult period in her past when she struggled with her esper development and sought a place to belong. The narrative reveals that the gang was originally a harmless group of Level 0s. Anti-Skill subsequently plans a major sweep of the Slum district of District 10 to crack down on Big Spider. Confronting Konori on a rooftop, Misaka learns the full history: two years prior, Big Spider's lieutenant, Hebitani Tsuguo, was taken hostage, leading the gang's leader, Kurozuma Wataru, to walk into a trap to rescue him. An explosion apparently killed Kurozuma, though he in fact survived with severe injuries and spent years in rehabilitation. Kurozuma reappears, stating his intent to dismantle the corrupted Big Spider himself. Konori, reaffirming that her feelings for him have not changed despite her position in Judgment, decides to get involved. On the day of the Anti-Skill sweep, Konori dons her old red leather jacket and is joined by Misaka and Kuroko, who place a Judgment armband on her. The three track Kurozuma to the Big Spider hideout, where he engages numerous gang members in hand-to-hand combat. Hebitani orders his men to fire, but their guns are disabled by Kuroko's teleportation darts, and Misaka destroys the Capacity Down device present in the room. After Kurozuma defeats the remaining thugs, Hebitani threatens to detonate a suicide vest, a bluff that Kurozuma immediately calls before incapacitating him. With the gang defeated, the group exits the building to await Anti-Skill. Kurozuma formally surrenders to Konori, who places him under arrest on suspicion of assault, a moment lightened by a brief, personal exchange between them. The episode concludes with Misaka and Kuroko on a rooftop, reflecting on the idea that personal connections can endure despite significant changes in people's lives and circumstances.

The episode shifts focus to Tsuzuri Tessou, a well-intentioned but often ineffectual Anti-Skill officer and teacher. After a series of frustrating failures during patrols, her colleagues, Aiho Yomikawa and Komoe Tsukuyomi, suggest she needs a hobby to alleviate her stress and improve her performance. This advice prompts Tsuzuri to revisit a childhood interest: an old arcade fighting game titled "Gekisho 9." At the arcade, she repeatedly encounters a middle school boy named Haruki Konoue, a classmate of Kazari Uiharu and Ruiko Saten who is also dedicated to mastering the same game. On her day off, Tsuzuri impulsively teaches him how to unlock a secret character before being called away to assist a drunken Yomikawa. A subsequent day of duty presents her with a series of unusual incidents, including encounters with a silver-haired nun (Index) and a shrine maiden (Aisa Himegami), which serve as continuity nods to the wider universe. Her responsibilities also involve helping a distracted girl search for a lost pendant. Returning to the arcade that evening, Tsuzuri is challenged to a match by Konoue, who has mastered the secret character and now poses a formidable opponent. After their game, she walks him home, and he offers a simple, awkward expression of gratitude. Days later, Tsuzuri learns from Uiharu and Saten that Konoue has transferred to a school specializing in game design, sponsored by the creators of "Gekisho 9". The revelation that her small act of guidance inspired him to pursue a concrete dream provides Tsuzuri with a renewed sense of purpose and satisfaction in her own role.

ITEM carries out an assignment against a group of mechs under the oversight of a mysterious organization. The episode then shifts focus to the personal lives of the main characters as they prepare for Banri's discharge from the hospital. Erii will be moving out of Uiharu's apartment to live with Banri, prompting a range of emotions within the friend group. The impending move creates a poignant subplot centered on Uiharu and Erii, highlighting the strength of their bond as roommates. Meanwhile, Kuroko and Uiharu are called away for Judgment duties due to a city-wide failure of traffic signals, which hints at larger, underlying events. Mitsuko Kongo utilizes her power to stop a purse thief but is subsequently berated by an unidentified man for her actions, suggesting the presence of unseen forces observing the city. Following the completion of their duties, Uiharu gives Erii a box of taiyaki as a memento, specifically recalling the day Erii first revealed her ability to her. The two share an emotional farewell as their time as roommates comes to an end. As the group takes a detour on their way home, they discover a mysterious white-haired girl named Febri asleep in a flower bed, who appears to recognize Misaka. This encounter introduces a new narrative arc, while the episode simultaneously depicts the mysterious organization initiating its next plan to demonstrate its power against espers.

The Tokiwadai dormitory hosts its annual Midsummer Festival, opening its doors to invited guests for various exhibits and events. Mikoto Misaka is tasked with a stage performance and struggles with increasing nervousness as rumors about her act spread among attendees. Kuroko Shirai is conscripted into kitchen duty by Maika Tsuchimikado, leaving Mikoto to guide their friends Ruiko Saten and Kazari Uiharu through the festival grounds. The tour includes various attractions, and the visitors learn of Mikoto's upcoming solo, which raises their anticipation and inadvertently adds to her anxiety. Children from Asunaro Park, accompanied by the Dormitory Supervisor, express their excitement for the performance, further escalating the pressure on Misaka. While preparing backstage, Mikoto encounters Touma Kamijou, who is searching for a lost acquaintance. Misaka misinterprets his presence as an attempt to mock her and reacts with forceful anger, chasing him away. This outburst effectively dispels her accumulated performance anxiety. Freed from her nerves, Mikoto proceeds to the stage and delivers a skilled violin solo of Elisa's "Real Force," captivating the audience. The episode concludes with the festival drawing to a close, highlighting the resolution of Mikoto's personal conflict and her successful performance.

The episode continues the pursuit of Saten Ruiko, who was taken under Frenda's protection after a previous abduction attempt. Frenda is shot by an unseen sniper while speaking with Saten, forcing them to take cover in a crowded department store. The assailant is Yumiya Rakko, a member of the organization SCHOOL, who systematically tracks the pair through the building. Frenda finds her usual tactics ineffective, as Rakko consistently predicts her movements and attempts to create diversions. Saten, recognizing that her lack of powers makes her a liability, volunteers to act as a decoy to expose their hunter. Saten walks directly towards Rakko carrying explosive dolls, which forces Rakko to react and reveal her position to Frenda. Frenda engages Rakko in close-quarters combat, using a thermobaric explosive to deplete the oxygen in the immediate area. As Rakko moves to a broken window for air, Frenda is waiting and expels her from the building with explosives. Saten is subsequently placed in Anti-Skill custody for her protection. In the aftermath, SCHOOL's leader, Kakine Teitoku, uses the information from Rakko's mission to identify the location of the "Tweezers" target. Rakko survives the explosion and expresses a desire for revenge against Frenda, but Kakine overrules her in favor of pursuing their primary objective. One week later, Saten awaits a promised visit from Frenda, but Uiharu Kazari arrives at her door with an injured arm instead, implying Frenda is unable to fulfill her commitment.

Following a Poltergeist incident at the park, the investigation into the earthquakes intensifies. Mikoto and Kuroko, acting on their own, conduct an illegal background check on Haruue Erii, the transfer student who has been staying with Uiharu. Their search reveals that Haruue is registered as a Level 2 Telepath, but official notes indicate her ability can exhibit power above her level when subjected to specific wavelengths. This information fuels Kuroko's suspicion that Haruue might be the involuntary cause of the destructive phenomena. Meanwhile, Uiharu takes Haruue to a park to offer comfort and a distraction from her distress. During their outing, Haruue reveals she is searching for a long-lost childhood friend. The moment of respite is shattered when Haruue suddenly falls into a trance, muttering to herself, which precedes another powerful Poltergeist event in the immediate area. Uiharu sustains minor injuries in the incident, deepening the conflict when Kuroko confronts her about Haruue's potential involvement. Uiharu fiercely defends her new friend, leading to a rare and intense argument between the two members of Judgment. To resolve the dispute, Researcher Therestina Kihara Lifeline proposes examining Haruue at the MAR facility to determine her connection to the AIM field interference. The tests conclude that Haruue is not responsible for the disruptions, a finding that initially seems to exonerate her. Upon waking, Haruue explains that she enters the trance upon hearing the voice of her missing friend, Edasaki Banri. Showing the group a photograph, Mikoto immediately recognizes Edasaki as one of the Child Errors who were students of Kiyama Harumi, the instigator of the Level Upper incident. Haruue then reveals that she herself is also a Child Error, a revelation that recontextualizes her situation and connects the current crisis to past events in Academy City.

Erii explains to Misaka and her friends that she and Banri are both telepaths who grew up together in a Child Error facility before Banri was transferred away, and she has recently been hearing Banri's telepathic cries for help. Uiharu attempts to comfort Erii by bringing her taiyaki and revealing her own ability, Thermal Hand, which allows her to maintain the temperature of objects she touches. Tension develops among the friends when Uiharu learns that Banri may be one of the comatose children from Kiyama's experiment and coldly rejects Kuroko's offer of assistance. Kuroko's research uncovers Kihara Gensei's theoretical paper warning that simultaneous resonance of AIM fields from multiple comatose espers could generate an earthquake powerful enough to destroy Academy City. Acting on this information, Misaka infiltrates one of Kihara's abandoned facilities and encounters Kiyama, who leads her to a secret hospital ward where all ten comatose Child Errors are being cared for by Heaven Canceller. Heaven Canceller reveals that he arranged Kiyama's release and gathered the children to develop a treatment, explaining that Kihara Gensei created Ability Crystals from extracted esper brain chemicals in an attempt to forge a Level 6, or SYSTEM, with the Child Errors as test subjects. Kiyama admits she is causing the Poltergeist incidents through her attempts to revive the children, whose powers run out of control whenever they near consciousness, and confesses she will wake them regardless of the destruction it might cause. Therestina arrives with MAR units and a warrant, demanding custody of the children for the safety of the city. Misaka chooses to side with Therestina, pointing out that Kiyama's methods have failed to save anyone, and informs Kiyama about Banri's suffering cries, forcing Kiyama to surrender her students to MAR custody.

Kazari Uiharu, motivated by concern for Haruue Erii, visits Dr. Kiyama to persuade her to cooperate with MAR, leading them to the MAR facility for a meeting with Therestina Kihara Lifeline. Therestina accepts Kiyama's research materials but immediately destroys them and refuses to allow any contact with the comatose Child Errors, including Erii. When a doctor addresses Therestina as "Dr. Kihara," she reveals her full identity as the granddaughter of Gensei Kihara and the original test subject for his Ability Crystal program, confirming her malicious intentions. Uiharu returns to the Judgment office in a state of shock, but Kuroko Shirai's forceful intervention helps her refocus on the task at hand. Acting on this new information, Mikoto Misaka confronts Therestina at the MAR base, only to be incapacitated by the Capacity Down device and overpowered by Therestina's powered suit. After Mitsuko Kongou secretly rescues the unconscious Mikoto, the recovered railgun attempts to continue the fight alone, blaming herself for the situation. Ruiko Saten physically blocks Mikoto's path and asks her to consider what she sees around her, reminding her that her friends are present and willing to help. The group reunites, reconciles their differences, and uses Judgment's satellite system to track Therestina's convoy heading toward District 17, also spotting Dr. Kiyama's car following the same route. They secure reluctant assistance from Anti-Skill officer Aiho Yomikawa, and as they prepare to depart, Uiharu makes a crucial observation on the satellite feed that will guide their intervention.

The episode opens with a flashback, revealing that Therestina Kihara holds a crystal labeled 'Sample 01', which was created from her by her grandfather, Gensei Kihara, years ago. In the present, Mikoto and her friends intercept a decoy convoy of Multi-Active Rescue vehicles, learning from Uiharu that the comatose children are being transported elsewhere. Kuroko and Kongou remain behind to engage the powered suits, while Kiyama drives Uiharu and Saten toward the children's true location, pursued by Mikoto and Konori. Therestina, piloting a large mecha, attacks the group on the highway, forcing Mikoto to defend the car from the roof. With Kuroko's teleportation assistance, Mikoto uses a severed mecha hand as a railgun projectile to disable Therestina's machine. The group locates the facility and finds Kiyama's students, including Haruue, sealed in tubes. Therestina activates the 'Capacity Down' device, paralyzing the espers in the room, but Saten, unaffected due to her Level 0 status, destroys the control system after Uiharu covertly directs her to it. Freed from the paralysis, Mikoto uses her powers to subdue Therestina, who then threatens to destroy the facility with her suit's built-in railgun. Mikoto counters the attack with her own railgun, defeating Therestina and obtaining the original ability crystal. Using the crystal, Kiyama successfully completes her treatment program and awakens her students. The episode concludes days later, with the recovering children broadcasting a birthday message to Kiyama via a city blimp, expressing their gratitude.