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Useful Spider (営巣部隊ユースフルスパイダー Eisō Butai (Yūsufurusupaidā)?, lit. "Nesting Unit") is a unit from Academy City's Disaster Recovery Committee, tasked with rebuilding the city following a major crisis.[1]


A unit under Academy City's Disaster Recovery Committee, Useful Spider's purpose is to rapidly rebuild Academy City and restore order following a major disaster which has caused city-wide devastation.[1] Once the primary danger is past, Useful Spider mobilizes to restore the city's infrastructure within a set time period.[1][2][3] During such a period, such as the 48 Hours to Restore Order (秩序回復の四八時間 Chitsujo Kaifuku no Shi Hachi-jikan?) following the Elements and December heat wave, Useful Spider operates on special authority which allows them to temporarily rescind human rights to secure dangerous individuals or items,[1][3] and carry out supposedly non-lethal suppression.[2]

Useful Spider makes use of vehicles described as Half-track (ハーフトラック Hāfutorakku?), with large beds on their backs. The front and rear wheels are powered in different ways; the rear wheels made into steel treads and the front wheels resembling countless insect legs wriggling around and digging to crawl or climb forward, working differently but moving in a way similar to the mouth of an ammonite or nautilus. The exposed truck bed has large speakers attached,[1] as well as gun turrets equipped with high-pressure water cannons for suppression purposes.[2] They also use helicopters, equipped with speakers and spotlights, armed with heavy machine guns positioned just inside the side cargo doors,[4] and liquid (possibly water or gelatin) for suppression via drops.[2]

Useful Spider also has a large number of 50cc AT carts, the size of one-person sofa, which can be used to set up a motor sharing service to aid the transportations of people and supplies.[5]

Useful Spider's headquarters is located in the mountainous School District 21, hidden under a large-scale meteorological observatory, which can predict coming disasters. The observatory has a Doppler radar dome on top, as well as thick electromagnetic shielding to protect staff and equipment from microwaves.[5]


The Sphere (スフィア Sufia?) is an information device distributed by Useful Spider,[6] designed to act as a disaster communication infrastructure base.[6]

As its name suggests, it is a metal sphere about 2m across which opens up in one direction like a lotus flower, becoming something resembling a planetarium with a faint layer of chemical smoke rising from its top, with hundreds or thousands of windows projected onto the smoke, forming a dome with a radius of 20-30m around the Sphere. The windows display information on other shelters, weather forecasts, which roads are blocked off, and progress for recovery work on infrastructure such as power and water, and distribution points for food and water.[6]

The key to the Sphere is a device resembling a USB stick which is inserted into a small slot on one of the petals and changes the screen to something resembling a browser on a normal computer with a virtual keyboard on the monitor inside the flower.[6]

The inner core of the Sphere contains a light splitting processor. Instead of using electricity, the processor makes use of the Zeeman effect, where light-emitting particles of a single wavelength split into multiples one on entering a magnetic field. When the waves collide, they combine, and by bringing multiple lights together in the small processor, their amplitudes can be used to represent 0s and 1s. The processor is a stepping stone towards quantum computers which use light separately as a wave and a particle.[7]

The Sphere's purpose is to form a disaster communication infrastructure base. With the Internet and phones down, misinformation is likely to spread, and radios and TVs may not be reliable. It is mostly made to receive news and administrative information, with its ability to send out information being limited to messages similar to posts on a message board, with the name of the sender, the shelter they are in and the time of the post. The system is like a social media account but with a broader framework; instead of individuals, the shelters or schools have a username for information exchange, and one individual (the 'ruler' of the shelter) operates the Sphere at one time. The communication infrastructure is meant to avoid misinformation and confusion, and therefore is designed to prevent people from sending out whatever they want, hence the Sphere network is not freely connected like a spider web, but more like a tournament diagram split into blocks with a thick line at the top.[6]

During the '48 Hours to Restore Order', Useful Spider supplied a Sphere to the shelters in the city. These named shelters included:

Name Location Notes
(裁判 Saiban?)
School District 7 Set up in a District 7 park, formerly planned to be the site for the Kigurumi Rock Festival which was due to be held on the day the Elements first appeared.[8][6][Notes 1]

The shelter's ruler was a middle-aged man in a work uniform, forced into the role. Once the crisis was past, the residents turned on him and would have executed him if not for Touma.[8][6] He was later killed by Aleister.[9]

(学会 Gakkai?)
School District 5 The largest shelter in District 5, housed in a college building made into a fortress with barricades, with more college students than middle and high school students.[10][3] In the center of the shelter, anonymous theories are pinned to a bulletin board, with the ones chosen as best determining the use of water and resources.
(博愛 Hakuai?)
School District 7 A shelter located inside a resort hotel in District 7, with focus on all three necessities; food, shelter and clothing.[11] The influence a person has is determined by the amount of charity given to others (with receiving help from others reducing influence, leading some to keep a low profile and avoid others' kindness).[11]
(健康 Kenkō?)
N/A One of the shelters infiltrated by the Kamisato Faction on December 9th. More than half of everything at Health is apparently about invisible jinxes and the occult.[12]
(監獄 Kangoku?)
N/A One of the shelters infiltrated by the Kamisato Faction on December 9th.[12]
Journalism (報道 Hōdō?) N/A A shelter run by a triumvirate. Journalism was one of the shelters infiltrated by the Kamisato Faction on December 9th, with Milcah overseeing it.[12] They tried to surreptitiously investigate the solar activity rumor, leading Maya to apply external pressure and spread half-truths to the people to cause the rulers' control to break down.[12]
Show Business (芸能 Geinō?) School District 7 A shelter located in a large boxy fitness gym.[12][2] Show Business generally decides things by majority rule but rather than one vote per person, a person has as many votes as they have fans, which also determines their class (including "regular", "center", "national" and "backup dancer"). This is likely due to the original school being focused on song and dance.[2]

The shelter's ruler is a tall cross-dressing girl wearing a naval coat with golden embroidery, with an androgynous look and an unknown esper ability.[2]

Hospital (病院 Byouin?) School District 7 A shelter based in Heaven Canceller's Hospital, which was safe from the Elements due to Heaven Canceller's efforts, and housed the students displaced from Tokiwadai Middle School following Yuiitsu's attack.[13]
(能力 Nōryoku?)
A shelter located near the boundary between School District 11 and District 7.[14][5] It was attacked by Useful Spider with the Breath of Blessing during Stage 3 of the '48 Hours to Restore Order'. The ruler and their aides sent the others to battle, wielding large water guns with pressurized pumps filled with oil or alcohol and ignited through Pyrokinesis, while they made their escape.[14][5]

One of the shelters' residents was an asthmatic girl with Level 3 Pyrokinesis, used as an ignition source for their fighting force, and her elder brother.[14]

Breath of Blessing[]

The Breath of Blessing (ブレスオブブレッシング Buresuobuburesshingu?) is a giant fan used by Useful Spider for suppression and clearing purposes.[3] The fans are giant cylinders about 20-30 meters wide, carried from helicopters by wires, of the class used in wind tunnel experiments to simulate wind speeds at Mach 7, and capable of blowing down reinforced concrete and small buildings.[3][5]

The fans were originally designed to designed to artificially alter wind direction and redirect toxic smoke away from densely populated areas in the event of a dangerous chemical fire in one of the city's laboratories, however this nonlethal firefighting usage was largely an excuse for paperwork.[9]


Shinyaku Toaru Majutsu no Index[]

Kamisato Rescue Arc[]

Main article: Kamisato Rescue Arc

On December 9th, following the end of the heat wave and the destruction of the Elements, Useful Spider were mobilized and distributed Spheres to the various shelters across the city, declaring the start of '48 Hours to Restore Order'.[1] Through the manipulations of Kihara Yuiitsu and the Kamisato Faction, they also declared Kamijou Touma and Karasuma Fran as wanted figures linked to the disaster.[1] The Spheres were used by the faction to manipulate the actions of the shelters' residents.[6]

When manipulations led the residents of the Show Business shelter to riot under the belief an ice age was coming, Useful Spider stepped in and started suppressing the rioters, causing considerable harm in the process. Touma attempted to seize the Sphere from Show Business's ruler to stop the riot but was knocked down before he could reach them. The rioters and Useful Spider forces were then incapacitated by an enraged Misaka Mikoto, driven by fury at the looters who had raided Tokiwadai Middle School and School Garden following Yuiitsu's attack.[2]

In the early hours of December 10th, Useful Spider moved into Stage 3 of the '48 Hours to Restore Order' and moved to collect any weapons and dangerous objects, deploying the Breath of Blessing in several areas, including the Academy and Esper shelters, and cutting off access to School District 11's container yard.[3][5] Later in the morning, they also set up a motor sharing service to aid transport of people and supplies around the city.[5]

In order to access the core of Anti-Art Attachment in the District 11 container yard, Touma, Fran and Toyama Luca planned to set off a delayed explosion at Useful Spider's headquarters in the District 21 observatory to draw their forces back while they accessed the container yard.[5] At the same time, the Kamisato Faction, deeming Useful Spider as an obstacle which was interfering with their search for Touma and risking their chance of saving Kamisato Kakeru, tracked them back to their headquarters and attacked the observatory.[15][16] Following the revelation of Fran's identity and her confession on the Sphere network,[17] she dropped the Bunny Grey Messenger onto the observatory.[18]

Not long after, Useful Spider found a memo from Touma that told them to help them if they wanted to resolve the situation and decided that it would be the best course of action to help restore the city.[19][20] Following the loss of the A.A.A.'s core, Useful Spider drew the Kamisato Faction's fire and brought Touma's group aboard one of their helicopters.[20] They helped to get them safely to Heaven Canceller's Hospital so they could use their alternative method to rescue Kamisato Kakeru and break Yuiitsu's hold over the Kamisato Faction.[21]

On December 11th, Useful Spider completed repairs to the city and declared the end of the '48 Hours to Restore Order'.[22]


  1. There are a number of dating discrepancies between volumes taking place during December. In Shinyaku Toaru Majutsu no Index Volume 16 and Shinyaku Toaru Majutsu no Index Volume 17, there are several references to the rapid onset of the heat wave and the Elements occurring on December 4th. This directly contradicts the events of Shinyaku Toaru Majutsu no Index Volume 15 and the previous two volumes. This article and the Unified Story Timeline proceed on the assumption that the references to December 4th in Volumes 16 and 17 are erroneous.


  • Kamachi Kazuma describes Useful Spider as a contrast to the Kamisato Faction, in that they were an important part of the story yet almost nothing was given about their names or what they looked like. He described how by making individuals fade away in a group, they seemed to gain a different sort of presence - faceless people who think normal things like normal yet do not hesitate to take action. He also thought that they might be a lot like what Kamisato Kakeru would have been if he had never gained a special power.[23]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 1 Part 5
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 2 Part 10
  3. 3.0 3.1 3.2 3.3 3.4 3.5 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 1
  4. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 8
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 4
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 1 Part 7
  7. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 2 Part 11
  8. 8.0 8.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 1 Part 6
  9. 9.0 9.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 3
  10. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 2 Part 2
  11. 11.0 11.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 2 Part 4
  12. 12.0 12.1 12.2 12.3 12.4 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 2 Part 9
  13. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 2 Part 12
  14. 14.0 14.1 14.2 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 2
  15. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 6
  16. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 7
  17. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 12
  18. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 3 Part 14
  19. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 4 Part 1
  20. 20.0 20.1 Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 4 Part 8
  21. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Chapter 4 Part 10
  22. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Epilogue
  23. Shinyaku Toaru Majutsu no Index Light Novel Volume 17 Afterword


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Academy City
Inhabitants Faculty and Staff Students
Factions and Organizations Board of Directors (Board Chairman) • JudgmentAnti-SkillCooperative InstitutionsUseful SpiderSkill-Out
Locations School Districts School District 1 (Administration) • School District 2 (Military & Law Enforcement Training) • School District 3 (Outsider Accommodation) • School District 4 (Food) • School District 5 (Universities and junior colleges) • School District 6 (Recreation) • School District 7 (Middle & High Schools, Student Accommodations, Hospitals) • School District 8 (Faculty Accommodation) • School District 9 (Industrial and fine arts) • School District 10 (Reformatory, Nuclear Research, Cemetery) • School District 11 (Goods transfer) • School District 12 (Theology) • School District 13 (Kindergarten and primary schools) • School District 14 (Overseas Students) • School District 15 (Shopping & Mass Communication) • School District 16 (Commerce) • School District 17 (Industry) • School District 18School District 19School District 20 (Sports and athletics) • School District 21 (Water storage & Observatory) • School District 22 (Underground development) • School District 23 (Aerospace)
Other Notable Locations School District 7: Windowless BuildingHeaven Canceller's HospitalA Certain High SchoolKamijou ResidenceSchool Garden (Tokiwadai Middle School)
Other: Imaginary Number DistrictReformatoryExternal Connection Terminals
Power Curriculum Program Esper (Level 0Level 1Level 2Level 3Level 4Level 5Level 6 (SYSTEM)) • Personal RealityEsper AbilitiesAIMSystem ScanLevel 6 ExperimentsParameter List
Notable Technology Tree DiagramHikoboshi IIBankAirshipCleaning RobotSecurity RobotWind TurbinePowered SuitNanodeviceSupersonic Passenger PlaneHard Science
Events (Timeline) Regular DaihaseisaiIndependence DayIchihanaransaiSummer City Flood Prevention ProgramAnti-Crime Orientation
Other 0930 IncidentInterceptor ShowAvignon Cleanup OperationWorld War IIIDecember Heatwave48 Hours to Restore OrderEvacuation of Academy CityOperation Handcuffs
Other ScienceExperiments and ProjectsChild ErrorMagic-Science TreatyAcademy City Military
See also: Dark Side of Academy City