ข้อมูลอนิเมะA Certain Scientific Railgun

Kuroko Shirai, a member of Academy City's Public Moral Committee, Judgment, is on the scene to apprehend a group of thugs harassing a girl only to find out the girl is not other than her sempai Mikoto Misaka who has already dealt with them. During this time, the city is holding a "System Scan" at several schools including Tokidawai Middle School. At Tokodawai, Mitsuko Kongo, a second year student mocks Kuroko and thinks she'll reach Level 5 before her only to witness Mikoto testing her powers at the School's pool which cause a giant explosion that can be seen and heard from afar. Kazari Uiharu, a colleague of Kuroko at Judgement and a fan of Misaka, is invited by Kuroko to meet up with Mikoto herself and brings along her friend, Ruiko Saten. In reality, Kuroko's main plan was to use Uiharu as an excuse so she could date Mikoto, but after finding her true purpose, Mikoto instead decides to bring them to a crêpe shop so she can get a Gekota key chain where a Tour Group are taking a break. Uiharu and Saten are surprise that Mikoto acts very nice and normal and not like the Rich Socialite image that they had in mind. Just then, a nearby bank is getting robbed and Kuroko goes into action to stop the robbers including one who is a Pyrokinesist. Meanwhile, as Mikoto and the others helps the civilians escape, they hear from a tour guide that a boy has wandered off from the group. Ruiko spots him being taken hostage by one of the escaping robbers and tries to stop them herself, getting kicked in the process. Taking it personally, Mikoto uses her powers to create her signature move, "The Railgun" to stop the robber's car from escaping. After the Robbers have been taken into custody by the City's Police, Anti-skills, Ruiko is praised by Mikoto, the tour guide, the boy's mother and the boy himself for her bravery.

Mikoto encounters Tōma Kamijō (the protagonist of To Aru Majutsu no Index) and corners him but he blocks her attacks and escapes. Deciding to keep quiet about it, she invites Kazari and Ruiko over to her dorms, ruining Kuroko's plans of celebrating her one month 'anniversary' of becoming Mikoto's roommate. However, Mikoto reveals that Kuroko forcefully sneaked into her room during that time. To make matters worse, after finding out Kuroko kept one of her panties, has a collection of perverted photos of her and learning Kuroko ordered aphrodisiacs for their "anniversary", Mikoto has a fight with Kuroko in the hallways but both stopped when the fearsome Dorm Supervisor arrives. As punishment for using their powers inside the dorms, both of them are sent to clean the school pool. Mikoto is introduced to Kuroko's classmates, Kinoho Wannai and Maaya Awatsuki, whom the former is an Aquakinesist that Mikoto saved from some thugs some time ago. Kuroko gets jealous of how well she gets along with others and cries believing Mikoto doesn't care about her. To cheer her up, Mikoto gives her a present celebrating a slightly different anniversary, the day when they became friends. However, whilst toasting, Kuroko accidentally drinks the aphrodisiac meant for Mikoto. She becomes so overcome with lust that she steals Mikoto's underwear whilst she is still wearing them, prompting Mikoto to repeatedly electrocute her as punishment.

Kuroko and Mikoto invites Kazari and Ruiko to go shopping and sightseeing at the School Garden, a private, high class district which caters for Schoolgirl's of elite and upper class schools and where most of the elite Girls schools are located. Ruiko gets her uniform wet after tripping into a puddle so Kuroko lets her borrow her Tokidawai uniform. When the girls arrive to an Italian Pastry shop for cake, Shirai and Uiharu are immediately called back at Judgment for an emergency. Mii Konori, their sempai in Judgment reveals that yesterday, six Tokidawai students including Mitsuko were mysteriously attacked by an unknown perpetrator with a Taser who immediately drew their eyebrows with a marker while they were unconscious but none of the victims saw their attacker. Unfortunately, it is during this time that Ruiko is mistaken as a Tokidawai student and attacked by the criminal herself whilst in the bathroom. As Mikoto, Kuroko and Kazari try to figure out who the invisible attacker is, they conclude that the attacker has an ability called 'Dummy Check', the ability to make the user invisible to the human eye, which explain why the victims never saw her but the district's CCTV camera's did. At first they believe the culprit is Miho Jifuki, a Sekishi Junior High student and the only person who has this ability but the City's database says she's only a Level 2 and doesn't have enough power to turn herself completely invisible. Saten, who has woken up after her attack and learning on what happen to her eyebrows, confirms Miho was the culprit who manage to see her face in the mirror before falling unconscious and wants revenge. With the help of School Garden's CCTV camera's, the girls manage to track Miho down and cornered her. After being subdued by Mikoto, Ruiko wants to draw Miho eyebrows but finds out the girl has naturally weird eyebrows. Miho reveals that she targeted Tokidawai students because her boyfriend left her for one and didn't like her eyebrows. Feeling sorry, Saten decide to let go of her grudge and ease Miho by telling her that her eyebrows are charming. As she's being taken away by the Anti-skills, Mikoto wonders how did Miho became powerful when she's only a Level 2 in the first place. The next day however, Saten is still angry that she didn't have her revenge against Miho when she learns the ink on her eyebrows won't come off for a week.

While the girls are discussing about urban legends, Mikoto isn’t impressed about Ruiko’s story about a woman who takes of her clothes in public, but takes an interest in a story about an ability that can cancels out other abilities. The story reminds her of her first meeting Tōma, when he tried to saved her from a group of thugs who were harassing her. At first she was impressed as he was the only one who tried to help, but she quickly got angry when he unintentionally insulted her and shocked everyone around her. To her surprise, her powers was ineffective against Tōma. Just as she was done thinking about it, Mikoto encounters Tōma giving directions to a woman. The woman randomly starts to take off her shirt in public because it’s hot and Tōma is mistakenly labelled a pervert by the crowd, forcing him to run away whilst Mikoto is left to deal with her. As Mikoto and the woman are resting at an outdoor cafe, Mikoto realizes the later is the infamous 'Undressing Woman' that Saten talk about. She later introduces herself to Mikoto as a researcher on Cerebral physiology and AIM (An Involuntary Movement), which Mikoto asks questions concerning about Tōma powers but the former has never heard an ability that can cancels out other abilities before. Meanwhile, after learning Mikoto met the 'Undressing Woman', the girls decide to rile up Kuroko by telling her about a curse that happens to girls who meet her. As Mikoto cleans the researcher skirt that was stained by ice cream inside the bathroom, she asks Mikoto to thank Tōma for helping her and concludes Mikoto might have feelings for Tōma from the way she talks about him, even labeling her as a tsundere. After she helps the researcher find her car, Mikoto encounters Tōma yet again and challenges him to a fight for leaving her with the researcher. As they battle near an embankment, Mikoto launches a direct electric shock which he manages to stop. She then creates a Chainsword by electro magnetizing the Iron sand on the ground and starts charging him and whips it but he manages to push it back and turn it back into iron sand. Mikoto sends a large cloud of Iron sand against Tōma, using it as a diversion to finally get close to attack him and grab his right hand. Just when she thinks she's won and tries to shock him, she is surprised when her powers don’t work (as unknown to her, Tōma’s right hand is the source of his power). Mikoto cowers thinking he’s going to hit her, but instead, Tōma decides to pretend he got shocked and falls to end the match. Unfortunately, Mikoto sees thru the ruse and angrily attacks him to force him to fight seriously and chases after him all night. As a tired Mikoto returns to her room, Kuroko, believing Mikoto’s under the 'Undressing woman' curse tries to 'cure' her but gets tied up instead. At the sametime, the researcher learns who Mikoto is.

While investigating a series of car break-ins, Kuroko and Uiharu encounter the culprit in the act but Kuroko rushes into action against Uiharu advice and gets knock out by the thief’s accomplice who was hiding inside the car. Uiharu tries to stop them but is tazered by the escaping thieves. Both of them get into an argument as Uiharu blames Kuroko recklessness for not listening to her to wait for backup. When Uiharu asks her about the promise they made, Kuroko doesn’t remember which angers Uiharu and causes her to storm off. Saten arrives at the Judgment’s 177th Branch Office to visit Uiharu who is currently in a foul mood which Mii Konori decides to explain how Uiharu and Kuroko became partners which, at the same time, a musing Kuroko tells to Mikoto. When they were still in grade school, Kuroko met Uiharu whilst both of them were training at Judgment. While on patrol with Konori, Kuroko felt she was being held back due to her age, but Konori that she needed to learn to work with others. To cheer her up, Konori decided to treat her and went to withdraw some money from the post office ATM’s, where Kuroko met up with Kazari again. However, Konori noticed a suspicious man carrying a gun, but failed to notify the staff before he made his move. Ignoring Konori’s orders, Kuroko quickly rushed to the bank robber and knocked him down. Unfortunately, the robber had an accomplice hiding among the crowds who had taken Uiharu hostage. With everyone distracted, the alarm was sounded, bringing the shutters down and activating a security bot. Kuroko again rushed towards the robber using the bot as cover, but Konori pushed her away when he destroys the bot, shielding her from the explosion and shrapnel. As the robber beat Kuroko, she blamed herself for being thoughtless and getting Konori hurt and Uiharu into this mess. She decided to save Uiharu by teleporting her outside while she keeps the robber trap inside. As Uiharu cried for help, the robber realized what Kuroko was planning but told her he could still escape thanks to his power “Equal Speed”, with which anything he throws will not stop no matter what obstacle is in its way, which he demonstrated by throwing a steel ball breaking thorough the shutters. He told Kuroko to use her powers to get the money in the ATM’s but she refuses, to which he responded by throwing a barrage of steel balls against her. But the balls were destroyed by an electrical blast shot by Mikoto, who anonymously answered Uiharu pleas. With the robber distracted, Kuroko used the opportunity to pin him down before he had a chance to act just as the police finally arrive. In the aftermath, Kuroko and Uiharu both promised with each other that they’ll help each other to become true to themselves and become better members of Judgment. Upon finishing the story, Kuroko realizes this was the promise Uiharu spoke of. When she gets a call from Konori that Uiharu has found the car thieves, with encouragement from Mikoto, Kuroko decides to go and help Uiharu.

Mikoto learns from Kuroko about a series of small harmless explosions in the city caused by graviton bombs where aluminum objects were uses as a catalyst. Unfortunately, the only suspect that has this ability was in the hospital during the whole time. Mikoto offers to help them investigate, but she is told by Kuroko to stay out of Judgment affairs. Mikoto tells her frustrations with Kuroko to Kazari in a cafe but she is dragged away by Kuroko, accidentally leaving behind her Judgment armband. When Mikoto tries to return it, she gets mistaken by Konori as another member of Judgment. Mikoto decides to play along to prove herself and show Kuroko she can be a better Judgment member. However, she’s surprised to find that a lot of Judgment work is menial, such as having to clean up after people, but she also gets to do her share of helping people in need, and it’s harder than she expected. Meanwhile, Kuroko and Kazari encounter a little girl who had lost her bag and calls Konori to help them search for the bag, which Mikoto assumes is related to the bombings and takes it seriously. Whilst searching, Mikoto encounters a boy being hassled by some thugs, who is very ungrateful for the rescue and instead is pissed off that she didn’t act quicker. They eventually find the bag being taken by a dog and Mikoto takes extreme measures to capture it safely, only to learn there wasn't a bomb threat in the first place. As Kuroko and Kazari return with the little girl to reclaim the bag, Mikoto's cover is blown, but she is thanked by everyone for her help nonetheless. Back at the Tokidawai Dorms, Mikoto reflects that being a member of Judgment isn't easy and has a new appreciation for what Kuroko and Judgment does, with Kuroko purposely misinterprets the saying and tries to harass Mikoto, but gets the door slammed into her back by the dorm supervisor who arrived to investigate the noise. Sometime later, two Judgment members evacuate a convenience store after detecting a graviton bomb inside but one them shields a civilian when the bomb goes off, causing a large explosion and seriously injuring him in the process.

With incidents involving graviton bombs becoming more frequent and bigger in scale, Judgment are asked to cooperate with Anti-Skill to investigate the matter. However, they are still unable to find any leads, given the minimum psychic level needed to pull off such a feat. Talking with Mikoto, Ruiko laments her lack of powers, thinking she wouldn't be helpful. She also mentions to Mikoto about a rumor concerning the Level Upper, which supposedly increases a psychic's power. The next day, whilst Kuroko continues to try and find a connection between the graviton incidents, Mikoto, Ruiko and Kazari go shopping at the mall. Whilst looking at a pair of pyjamas, Mikoto runs into Tōma, who is accompanying the little girl she met the other day. Meanwhile, Kuroko discovers that the graviton attacks are targeting Judgment members, and when she detects the vibration of graviton particles in the mall, she soon realises that Kazari is the next target. As civilians are evacuated from the mall, Tōma informs Mikoto that he had lost track of the little girl. They re-enter the mall to find her giving a stuffed doll containing a graviton bomb to Kazari. As it goes off, Mikoto tries to shoot it with her railgun, but fumbles her coin, leaving the explosion to take place. However, nobody gets hurt, and Mikoto finds and beats the culprit, a bullied boy who had become hateful of Judgment's late arrivals. Whilst everyone believes Mikoto saved everyone, it was actually thanks to Tōma's Imagine Breaker that everyone survived.

Kazari gets a cold and cannot go to school, but Ruiko, Mikoto and Kuroko pay her a visit. Kuroko is curious how Hatsuya, a level 2 esper, had powers equivalent to a level 4's. Mikoto brings up the Level Upper urban legend Ruiko had mentioned, and Kuroko points out this is not the first time a user's power and the user's level have been vastly different. Kazari finds out via an Internet forum that a restaurant in town is where information on the Level Upper may be found. Mikoto and Kuroko go to investigate, and Mikoto acts like a cute, interested girl to get a few guys to tell her about the Level Upper. Mikoto eventually gives up the act and after taking care of the guys and their friends, their leader arrives, though Mikoto gets away unscathed, though in the process causes a city-wide blackout. The next day, Kuroko and Mikoto discover that Hatsuya, along with several others who have shown abnormally strong powers, have all fallen victim to lapsing into comas. Meanwhile, Ruiko discovers the Level Upper by chance.

Mikoto and Kuroko talk with Harumi Kiyama, the specialist Mikoto had previously met, about the Level Upper. They are later joined by Kazari and Ruiko, the latter of which has the Level Upper, but decides to keep it to herself. Mikoto later catches up with Ruiko, noticing she's a bit down. The next day, Ruiko stumbles upon someone being conned by three thugs over the Level Upper and can't bring herself to just run away. Kuruko coincidentally arrives before she gets hurt and subdues two of the thugs, but has trouble using her teleport powers against their boss due to his ability to distort light. He chases Kuroko throughout an abandoned building, but is defeated when Kuroko teleports windows to cut through the building's supports and bring the place down. Having barely just survived, the thugs surrenders his Level Upper to Kuroko. Later, Ruiko encounters some of her friends, and reveals to them that she has the Level Upper.