Toaru Majutsu no Index Wiki
Pentagram-GreatGold.png Series Three Overhaul Project
This article will be undergoing extensive revision as part of a wiki-wide overhaul

Jailbreaker Arc (獄門開錠ジェイルブレイカー Jeirubureikā-hen?) is a story arc in the Toaru Kagaku no Railgun manga series, covering chapters 98 to 130.

The story focuses on a jailbreak trial organized by the operators of a new private juvenile hall in Academy City in order to test the facility's security features. The challenge is to break into the facility and successfully extract the target prisoner, with a one billion yen reward for successful completion.[1] Various people wish to take advantage of the opportunities presented by this event, both openly and secretly.[1][2][3][4]


The New Juvenile Hall

The new juvenile hall was the second such facility set to open in Academy City, but unlike the publicly-run Reformatory, this juvenile hall was run by a private security business. It was built in response to a rise in crimes committed by espers as opposed to those involving Skill Outs and a belief that the private firm could provide a better service than the publicly-run facility.[1]

Facility Layout

The outer wall is 15m tall and encloses the facility in the shape of a right trapezoid. There are two entrances; the main gate where suspects are brought in and which staff use to go in and out, and a back gate which is normally kept closed and only opened in emergencies. The main gate is the only one which vehicles can pass through.[2] It is apparently 1.8 times as strong as the previous Reformatory's gate and there are two additional shutters of the same strength which can be closed behind it.[3] Wind machines installed in the wall can be used to blow projectiles off course.[3] There are pipes running through the wall, which carry a fast hardening filler known as Birdlime (バードライム Bādoraimu?) to rapidly seal up any holes made in the wall.[3] There are also sensors and defenses in the wall ducts.[2] In the grounds between the perimeter fence and the outer wall, aside from robots, there are numerous acoustic weapons and adhesive pitfalls.[2]

The prison and holding centers are both located within the walls, with an internal division between the two, so as to keep prisoners under the effects of the jammers while being transported between them. For some cases, trials are held online with the prisoner remaining in the facility throughout.[2]

The juvenile hall has over a dozen AIM Jammers, the effects of which fully cover the region within the walls and reach approximately 20m outside them.[1][2][3] As well as the standard AIM Jammers, there is also a pinpoint long-range jammer which can be used against targets outside the facility walls.[3] The standard jammers consist of a sphere, vaguely resembling a disco ball, encased within a translucent pyramid on top of a platform, with several rods holding the sphere above the platform from below, over a round hole.[5]

The juvenile hall's electronic security system was supposedly put together by Academy City's highest level engineers and AI.[6]

The juvenile hall has a large complement of guard robots, which come in several varieties:[2][3][7][5][8]

  • The standard guard robots have a domed body on a crescent-shaped base with three legs and a translucent front covering sensors and circuitry.[2][3][7] A weapon block is located on the left side of the robot, capable of firing impact rounds, electrified nets and liquid shots.[2][3] There is also a variant which is equipped with a rubber bullet gatling gun instead.[8] The robots are also equipped with speakers and bar scanners.[2] They can travel along the side of the wall on their base, with their legs folded up behind them.[3]
  • There are larger, bipedal robots, referred to as war armadillos, which are also capable of moving around rolled into a ball. They are equipped with a heat blade and air gun held in arms behind the head, as well as an acoustic weapon housed in the chest.[3][7][6] Meant to keep intruders out, they are stationed at the outer wall.[9]
  • Type: Hunting Wasp (タイプ:ハンティングワスプ Taipu:Hantingu Wasupu?)(T:HW): Flying riot suppression robots in the shape of wasps, with a stinger which injects a sleeping drug.[5][Notes 1][10][11]
  • Type: Giant Centipede (タイプ:ジャイアントセンチピード Taipu:Jaianto Senchipīdo?)(T:GC): A robot in the shape of a giant centipede, which constricts targets to restrain them.[5][Notes 1][10][11]
  • The largest of these security robots, referred to as riot suppression gigapedes, are stationed inside the prison buildings.[8][9] Being a robot operating in the solitary confinement area and well within the jammer range, it is intended to deal with inmates who are unable to safely use their esper abilities.[6]

There are also quadrupedal guide robots within the walls, designed by Kyougoku, which have his face on them and somewhat resemble a jinmenken.[7][5]

The Jailbreak Trial

In order to promote the new juvenile hall and test its security features, Director Kyougoku Ryouta invited interested espers to challenge the facility and search out vulnerabilities in a Jailbreak Trial (脱獄トライアル Datsugoku Toraiaru?). The objective of the challenge was to break into the facility, find and retrieve a target prisoner (played by one of the jailers and located in the girl's building),[1][5][6] and then break out of the facility with them. The reward for successfully completing the challenge was one billion yen.[1]

The exact victory conditions have been noted to be somewhat vague, likely because the organizers didn't expect anyone to complete the challenge successfully.[7] However the facility's defenses were to operate at combat specs during the event, and competitors had to sign a liability form, stating that the organizers were not responsible for any injuries or death occurring as a result of their participation.[2] The rules state that competitors don't have to use the main gate and if they are using equipment too large to carry, to pick it up from the neighboring parking lot.[2]

During the trial, the actual prisoners were apparently moved to the bottom two levels of the prison building basement, while the test prisoner was positioned alone on the top level of the basement.[6]

During the interview where he announced the jailbreak trial, Kyougoku boasted that his company had built defenses to hold even a Level 5 and that even if the likes of Tokiwadai Middle School gathered all of their students, he doubted they'd even breach the first wall.[1] This prompted several Tokiwadai students to enter, including Misaka Mikoto.[1][6][Notes 2]


The challenge and its rewards attracted 4,378 people from various backgrounds and using a variety of methods to attempt the trial.[1][2][3][7][6]

Notable competitors include:

Name Background Notes
Misaka Mikoto Tokiwadai Middle School #3 Level 5 and Academy City's strongest Electromaster. Entered due to the aforementioned provocation.[1]
Shirai Kuroko Tokiwadai Middle School
Level 4 Teleporter. Entered to keep an eye on Misaka Mikoto.[1]
Uiharu Kazari Sakugawa Middle School
Level 1 Thermal Hand and Goalkeeper. Right arm healing from injury and in a sling.[2] Trial Winner. Won by hacking the prison system, taking control of a group of robots, riding them to the building, accessing the prisoner and riding out with them, having replaced security camera footage with dummy footage to conceal her escape. Donated prize money to Asunaro Park.[6]
Saten Ruiko Sakugawa Middle School Level 0. Entered due to the reward.[1] Brought paw-shaped gloves for climbing purposes.[2][3][5]
Kongou Mitsuko Tokiwadai Middle School Level 4 Aero Hand. Brought absorbent material suits, used by the Kongou Conglomerate to avoid affecting readings when working in anechoic chambers for aircraft development, in order to fool various sensors. Brought the suits in suitcases in separate parts and equipped once inside the wall.[6]
Wannai Kinuho Tokiwadai Middle School Level 3 Hydro Hand. Accompanied Kongou Mitsuko and also used an absorbent material suit.[6]
Awatsuki Maaya Tokiwadai Middle School Level 3 Float Dial. Accompanied Kongou Mitsuko and also used an absorbent material suit.[6]
Kouzaku Mitori Shokuhou Misaki's faction Level 4 Liquid Shadow.[1] Brought her tablet and remote drones along.[2][5]
Dolly Shokuhou Misaki's faction Clone of Misaka Mikoto and Electromaster.[1][2] Wearing concealing hat and tracksuit.[2][5]
Fusou Ayame Roadside artist Ability involves amplifying her voice to create explosive shockwaves. Entered as she is deep in debt on a speaker truck bought to reinforce her power.[2]
Oumi Shuri Kouga School of Ninjutsu Ninja. Entered with comrades as part of a mission to locate powers and technology in Academy City which could be used by the Kouga.[7]
Asai Kouga School of Ninjutsu Ninja. Entered with comrades as part of a mission to locate powers and technology in Academy City which could be used by the Kouga.[7]
Sakata Kouga School of Ninjutsu Ninja. Entered with comrades as part of a mission to locate powers and technology in Academy City which could be used by the Kouga.[7]
Yasu Kouga School of Ninjutsu Ninja. Entered with comrades as part of a mission to locate powers and technology in Academy City which could be used by the Kouga.[7]
Tsurigane Kouga School of Ninjutsu Ninja who infiltrated Academy City posing as a Child Error. Entered with comrades as part of a mission to locate powers and technology in Academy City which could be used by the Kouga.[7] Actually part of a group who are using the event to carry out a real jailbreak.[4]
Leader Scavenger Level 3 Predator. Planned to let another team reach the prisoner, then steal the prisoner from them on their way out. Expected Misaka Mikoto's group to have a strong chance of doing so and assigned Yakumaru to monitor them.[7][5][6]
Yakumaru Scavenger Ability to separate liquids by manipulating their specific gravity. Assigned to monitor Misaka Mikoto's group on behalf of her team.[5][8][9][6]
Naru Scavenger Level 3 paper-based Psychokinesis.
Seike Scavenger Ability involves control of coefficient of friction.
Junta His gang Entered with Part-time ironworks workers and defeated by the acoustic weapons outside the wall.[2]
Yamashiro Shoubu Masked Heroes Wears a black student uniform and a tanuki mascot mask (apparently Ponkichi-kun from Win Win Sentai) which fully conceals his face.[2][8] Proclaims himself as one of Academy City's masked heroes.[4] Wields a wooden sword.[2][8] Has the ability Stress Dowsing, which allows him to sense a target's malice and hostility.[4]
Raifu A little girl with baggy sleeves.[2] Actually part of a group who are using the event to carry out a real jailbreak.[4]
Robot club members Robot club Members of a robot club who developed exoskeletons/Powered Suits.[3]
Part-time ironworks workers Ironworks workers A group who work part-time at an ironworks, where they made an armored car. Defeated by the acoustic weapons outside the wall.[2]


This section requires expansion
Ch106, 116, 118-120, 126, 129


This section requires expansion
All sections


This section requires expansion

The Outer Wall

This section requires expansion

Inside the Wall

This section requires expansion

Prison Building

This section requires expansion


This section requires expansion


This section requires expansion


This section requires expansion


This section requires expansion

Battle at the Wall

This section requires expansion


This section requires expansion


  1. 1.0 1.1 The insectoid robots follow the same Type: naming pattern as the robots used by Baba Yoshio.
  2. Given that the jailbreak trial is a physical event with AIM Jammer interference, Shokuhou Misaki didn't take part, apparently stating that only a simple-minded fool would fall for such a cheap provocation, though at least two of her friends decided to compete, with at least two others watching over them.



v  e
Story Arcs
Toaru Majutsu no Index Academy City Arc Index ArcDeep Blood ArcSisters ArcAngel Fall ArcThree Stories ArcKazakiri Hyouka ArcOrsola Aquinas Rescue ArcTree Diagram Remnant ArcDaihasei Festival Arc
Versus Roman Catholic Church Arc La Regina del Mare Adriatico ArcAcademy City Invasion ArcSkill-Out UprisingDocument of Constantine ArcBattle Royale ArcAcqua of the Back ArcBritish Royal Family ArcDRAGON ArcWorld War III Arc
Shinyaku Toaru Majutsu no Index Gremlin Arc Freshmen ArcHomecoming ArcHawaii Invasion ArcBaggage City ArcIchihanaran Festival ArcAgitate Halation ArcMagic God Othinus Arc
Fall of Academy City Arc Mental Out ArcSt. Germain ArcMagic God Invasion ArcWorld Rejecter ArcSalome ArcElement ArcKamisato Rescue ArcAleister Crowley ArcProcessor Suit ArcCoronzon ArcKamijou Arc
Souyaku Toaru Majutsu no Index R&C Occultics Arc Christmas Eve ArcChristmas Day ArcOperation Handcuffs ArcLos Angeles ArcPost-Handcuffs ArcNew Year's Eve Arc
Toaru Kagaku no Railgun Level Upper ArcBig Spider ArcAPoltergeist ArcASisters ArcSilent Party ArcADaihasei Festival ArcDream Ranker ArcJailbreaker ArcFirst Year Arc
Toaru Kagaku no Accelerator Necromancer ArcNectar Arc
Astral Buddy Astral Buddy Arc
Toaru Kagaku no Dark Matter Yuzuriha Ringo Arc
Toaru Kagaku no Mental Out Tokiwadai Election Arc