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Kuriba Ryouko, who was split in two cyborgs for a year as part of the experiment.

The Total Human Cyborg Replacement Project (人体のサイボーグ全置換プロジェクト Jintai no Saibōgu Zen Chikan Purojekuto?, lit. "Human Body Cyborg Full Replacement Project") was a cyborg experiment carried out in Academy City.[1][2][3][4][5]


The project was an experiment which was meant to test various forms of cyborg technology and its compatibility with the human body over the span of a year, gathering data from the cybernetic treatments to aid in further development. The test subject was cyborg researcher Kuriba Ryouko, who had volunteered in order to gather data for the many different cybernetic parts which would be necessary to save her ill mother, who had only a couple of years left to live.[1][4][3][6]

In the experiment, Kuriba's body was cut up into pieces and the separated human parts combined with mechanical parts to produce two cyborgs.[1][4][3][6] The two lived separately for a year, with data being gathered throughout this period.[1][4][3][6] The set-up meant that data could be collected from every part of Kuriba's body, and being a cyborg researcher herself, she was able to act as both test subject and observer.[3][6]

The cybernetics used in the experiment incorporated technology which Kuriba herself had developed, including safety limiters which would prevent the cyborg body from performing actions which would damage itself beyond a permissible level, artificial muscles which used chemical reactions to expand and contract, and suppressant materials to prevent rejection from flesh towards the machinery bonded to it.[7][6]

After a year had passed, Kuriba was combined back into one person, with the mechanical parts removed.[1][4][3][6] She retained both sets of memories from the time she was split apart, with no mental split.[1][4] There was no physical rejection and although in a wheelchair immediately after surgery, Kuriba was soon back on her feet - being out-of-shape and not getting sleep afterwards was mainly due to her own focus on her urgent work.[1][8][7][4][6] She was prescribed high-quality Miahilin to deal with potential after-effects from the cybernetics.[7][6]


Although testing and observing cybernetics and their compatibility with the human body was the experiment's primary objective, unknown to Kuriba the research institution also hoped to observe a side-effect - the creation of a soul (魂の生成 Tamashī no Seisei?).[1][4]

The idea and question behind this hidden objective (which Shokuhou Misaki described to Misaka Mikoto while explaining the experiment) was that supposing there was a phenomenon known as the soul, what would happen to the soul when the test subject was split into two. As it seemed hard to imagine that one of the two would simultaneously die if other one happened to die while they were separated, it was supposed that when the test subject's body was physically split and made into two cyborgs, the soul would also be split and doubled. With one soul having become two, when the two bodies were made one once more and with one soul residing in it, the next question was what would happen to the leftover soul, with the possibility of it coming to reside in a body made from the assembled mechanical parts left over from the two cyborgs.[1][4]

After Kuriba Ryouko had lived as two separate cyborgs for a year, she was recombined back into one body and the leftover cybernetics were combined into one mechanical body.[1][2][8][4] The result was what researchers called the Doppelganger (ドッペルゲンガー Dopperugengā?), a mechanical duplicate of Kuriba Ryouko, who believed herself to be the real one and perceived herself as such, which the researchers considered the realization of their hopes.[8] The Doppelganger possessed Kuriba's knowledge, but only possessed memories from since the start of the experiment.[2][4]

When considering the risk posed by the Doppelganger, although not fully convinced about the soul, Kuriba Ryouko theorized that unlike other souls, thought to be linked to the body and destroyed when it ceases to function, the Doppelganger's soul was merely stored inside the mechanical body and if the container was destroyed, it would be freed from its restraints and spread to its surroundings. She also theorized that the abnormal "free soul" (自由な魂 Jiyūna Tamashī?) would be able to possess anything or possibly, in the worst case scenario, engulf the city itself.[7][6]

However, shortly after discovering her true identity, the Doppelganger came to the realization that she did not have a soul and was just an artificial intelligence.[9][10][11] Having predicted the soul diffusion theory which her original would consider, the Doppelganger used its calculative ability and assimilated intelligence and creativity to incorporate the theory into its plans.[9][11] During its attempt to destroy the means to recreate herself and bring about her own destruction, she utilized self-replicating artificial muscles, created from materials at the abandoned Shinasame University DNA Map Analysis Laboratory,[8][4][9][11] and incorporating traits from slime molds, ant parasite fungi and gorilla muscles,[9][10][11][12] which gave the illusion of soul possession (魂の憑依 Tamashī no Hyōi?), on top of augmenting her capabilities.[3][13][14][15][9][6][16][11]

The Doppelganger and others ultimately concluded that there was no created soul and the researchers' conclusion that one had been generated was merely the result of wishful thinking.[9][10][11][17] However, there was a notable after-effect of the incident. After some of the destroyed Doppelganger's parts were placed into Kuriba following her gunshot wound, the Doppelganger started appearing in her dreams, displaying knowledge and behavior which only the Doppelganger would possess and which Kuriba had no way of knowing, such as that of the Doppelganger's battle with Misaka Mikoto.[18][17]

Facility, Staff and Airship[]

The skyscaper housing the lab.

The research institution which carried out the experiment was based in a skyscraper (which had a triangular gap in its outer cladding around one corner), with its laboratory in the bulbous top floors of the high-rise building.[2][4] The lab contained the capsules and equipment necessary for the disassembly, reassembly and monitoring of the test subjects, as well as living quarters.[2][3][4] An outer corridor surrounded the lab, with windows looking out onto the city. The lower floors of the building apparently had layered security.[8][4] There were a number of steel banners around the base of the building.[2][4]

Besides Kuriba Ryouko, who was both researcher and test subject in the experiment, there were numerous other researchers involved on the project, who were aware of and hoped for the other possible product of the experiment.[2][8][4] The chief researcher was a man who had initially sought to develop a cheap cyborg method for medical refugees, but had eventually strayed.[10][17] Another notable member was a female researcher, who was involved in hiring Scavenger to retrieve the escaped Doppelganger.[8][4][13][14][16] One of the institution's sponsors was connected to the Academy City Board of Directors.[19]

The research institution had an off-site back-up in the form of a catamaran-style airship, equipped with polarizing deception technology to conceal itself. Once a month, the airship passed through a specific location for an exchange of information via laser, but followed random flight paths for the rest of time, such that not even the institution itself knew where it was.[20][16]


Kuriba Ryouko, about to enter a life-support tank to be split apart

The experiment was devised at a certain institution in Academy City, which had initially had trouble finding volunteers, given its unprecedented nature. Kuriba Ryouko, who was working at the institution in order to develop a cyborg treatment for her mother, ended up volunteering for the experiment to gather the necessary data in the short time she had left.[3][6] Her body was subsequently split in two and the missing parts replaced with machines to create two separate cyborgs.[1][4] Acting as both observer and specimen, she planned to use the experiment to gather data on every part of the body.[3][6] After a year living apart, the two were recombined into one, with no split personalities or rejection, and retaining the memories of the time split apart.[1][4]

Kuriba learns about her doppelganger

After being recombined, the researchers showed Kuriba Ryouko the Doppelganger formed from her combined cyborg components, one who believed herself to be Kuriba Ryouko,[8][4] and the product of the researchers' hope to observe the creation of a "soul".[1][8][4] Although not fully convinced, she warned the scientists of the potential risks, theorizing what might happen if the mechanical body was broken and the created "soul" released. The researchers ignored her, believing the safety measures and security in place to be sufficient and believing that the event of the Doppelganger realizing her true identity would merely be an opportunity to gather additional data.[8][4][7][6]

While working on the cybernetics for her mother,[8][3][4][6][14][15] Kuriba tried to find a solution to the problem posed by the Doppelganger and the "soul" but was unable to find one. She subsequently spread Indian Poker and some of her own knowledge, in the hopes that it would eventually lead to a solution.[1][4][7][3][15][10][11][17]

The Doppelganger realizes what she is.

About a month after the recombination,[2][4] having been kept in the lab under the pretext of observation for after-effects,[2][4] the Doppelganger noticed that she could not recall any memories from before the experiment,[2][4] and realized her true nature, as well as the fact that she didn't have a soul.[2][9][10][4][11][17] She subsequently sought her own termination, but was unable to terminate herself due to safeties built into her mechanical body,[10][17] so she made a plan to escape from the laboratory, destroy the means to recreate her (her creator, the lab's data and the off-site back-up), and bring about her destruction (intending to trigger Academy City's interception system against the data storage airship),[8][4][9][10][11][17] predicting and taking into account the soul diffusion theory which her original was likely to consider.[9][11]


Dream Ranker Arc[]

Main article: Dream Ranker Arc

The Doppelganger passes by Mikoto while falling during the escape.

Following the trail of the Indian Poker cards, Shokuhou Misaki learned of Kuriba Ryouko and the experiment she participated in, and shared this information with Misaka Mikoto.[1][2][4] As Mikoto was heading to investigate the facility, the Doppelganger escaped from the building, destroying her GPS, adhesive restraints and the on-site research data in the process.[2][8][4]

The Doppelganger, in the abandoned lab, having acquired some artificial skin.

While Mikoto and Shokuhou visited the original Kuriba Ryouko, the researchers hired Scavenger to retrieve the Doppelganger.[8][7][4] Meanwhile, the Doppelganger visited the abandoned Shinasame University DNA Map Analysis Laboratory and used its resources to construct the self-replicating muscles she would use in her plan, as well as acquiring some artificial skin.[8][4]

The Doppelganger corners the original.

Accessing a pharmaceutical database, the Doppelganger tracked down Kuriba through her Miahilin prescription, cornering her out-of-shape original as she was picking some up from a locker. Kuriba managed to escape by using a device she'd built as a countermeasure to make a smokescreen and temporarily bind the Doppelganger's arm.[7][6]

Naru damages the Doppelganger while saving Leader from her grasp.

The Doppelganger was then attacked by Scavenger, who managed to temporarily restrain her. However, while being taunted by Leader, she broke free with her augmented capability and snapped Leader's arm. As she moved for Leader's eye, Naru reacted with a blow that broke the right side of the Doppelganger open. Though knocked down, the Doppelganger soon got up and used its 'soul possession' to seize Naru's paper and rubble to patch up her broken side, and overwhelm Scavenger, who were forced to escape.[7][3][6]

The patched-up Doppelganger using her 'soul possession'.

The Doppelganger headed to connect lines to high-pressure gas tanks as part of her plan. While there, she was found and confronted by Mikoto and Leader, the latter having convinced the former to work together with her under a pretence. After a short clash, the Doppelganger threw an old gas tank at them to make them temporarily fall back, before heading towards a radar facility, intending to use it to locate the data storage airship, assimilating more material along the way.[13][16]

Leader threatens the researcher to sign the contract.

Realizing that the Doppelganger's route took her near the warehouse Scavenger were meant to deliver her to, Leader convinced Mikoto to divert the Doppelganger's route. After a few preparations, Scavenger met with the female researcher and presented her with the approaching Doppelganger, with the news reminding her of Kuriba's theory. Completing their mission on a technicality and forcing the researcher to sign the form, Scavenger escaped just before the Doppelganger destroyed the warehouse on its way through.[13][16]

The chief in shock at the sight of the Doppelganger's giant puppet in the distance.

As Mikoto continued to fight and analyze, the Doppelganger gathered a huge amount of debris into a giant puppet which her foe could not break or burn so easily, the sight of which shocked the project chief, initially incredulous at the 'soul possession' his subordinate was telling him about over the phone.[14][16] Around the same time, Kuriba completed and sent off the basic design for her mother's cybernetics, so that her mother could be saved even if something happened to her, and heading out.[14]

Mikoto fights the Doppelganger's giant puppet with her iron sand one.

After dealing with a building the debris puppet knocked down towards her, Mikoto responded with her own giant iron sand puppet, as the Doppelganger emerged in a repaired and altered form.[14][11] As Mikoto managed to get the upper hand, the Doppelganger threatened to drop gas tanks on the city, forcing Mikoto to intercept them with iron sand bullets. As a result, iron sand filled the skies of Academy City and fell on the airship, resulting in solar wind and magnetic interference disturbing its stealth, enabling the Doppelganger to locate it.[15][11]

The Doppelganger's influence finally reaches the airship.

The Doppelganger then broke down the debris into numerous decoys and descended among them while preparing to reach for the airship.[15][11] As she was connecting to it, Kuriba arrived and said she wished to speak with her. The Doppelganger subsequently took her up to the airship, spreading her muscles on arrival and forming a growth at the stern, the main line for manipulating gas tanks and triggering the interception system, which Mikoto (who had glimpsed and slice some of the muscles) managed to grab and hang onto.[15][11]

Kuriba then asked the Doppelganger to give her two months, explaining about Indian Poker and the plan to find a method for erasing a soul, clarifying that she intended to use it on herself. Expressing doubt that she'd hand over her body like that, the Doppelganger replied that she had no interest in it and just wanted Kuriba to disappear, claiming to be willing to burn the city to achieve it, telling her to prove her words by dying there.[15][11]

Kuriba lets herself be blown off from the airship.

In response, declaring that she was meant to die long ago and her mother was now safe, Kuriba let herself be blown off and fall from the airship. Though she was beyond Mikoto's range, Scavenger had been observing and caught her mid-fall.[15][11] They then dropped her off where the project chief was fretting over the interception system firing on the airship, having been on the phone to a sponsor connected to the Board of Directors to reassure them.[9][11]

At the same time, Mikoto continued her climb, and while speaking with Shokuhou and Leader, confirmed her guess about artificial muscles being behind the so-called 'soul possession'. On reaching the airship, she burned off the growth at the stern, severing the main line, while guessing her foe's motivation. Revealing and wielding her asset openly, the Doppelganger fought Mikoto with twenty minutes left for the sub-lines to grow enough to manipulate the mass of the gas tanks.[10][17]

A massive thundercloud engulfs the airship, destroying it and the Doppelganger.

By then, Mikoto had realized the Doppelganger's true intentions, confirming it when the Doppelganger positioned herself directly in the firing line of a railgun shot. On being asked if she could not live as she was, the Doppelganger spoke of the agony of her existence and managed to convince Mikoto to end her suffering, both Doppelganger and airship being brought down by a massive thundercloud.[10][17]

Kuriba sees the wreckage of both the Doppelganger and the airship.

The chief holds Kuriba at gunpoint, not believing the Doppelganger has no soul.

Arriving afterwards with Kuriba and seeing the wreckage of the airship and the Doppelganger, the research chief attempted to salvage the remains despite the girls' pleas to let the Doppelganger rest, threatening Kuriba at gunpoint to force their cooperation and refusing to believe that the Doppelganger didn't have a soul. After accidentally shooting Kuriba in the abdomen as she tried to convince him to stop, he fled the scene and intended to repeat the experiment, possibly using Child Errors. However he was apprehended by Shokuhou using Mental Out. Learning of his original goal before he strayed, Shokuhou decided to help him recall his original intentions and that if he wished to redo things, he would have to crawl back up from below where he started.[10][17]

The Doppelganger appears in Kuriba's dreams.

In the aftermath of the incident, the research institution went out of business, denying Scavenger their payment, though they were able to negotiate with their liaison to restore their lost rank. Intact parts from the Doppelganger were used to save Kuriba's life and afterwards the Doppelganger started to appear in her dreams.[18][17]

Known Participants[]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Toaru Kagaku no Railgun Manga Chapter 085
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Toaru Kagaku no Railgun Manga Chapter 086
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Toaru Kagaku no Railgun Manga Chapter 089
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 4.30 4.31 4.32 4.33 Toaru Kagaku no Railgun T Episode 21
  5. Ogino Kentarou, Twitter
  6. 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 6.12 6.13 6.14 6.15 Toaru Kagaku no Railgun T Episode 22
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Toaru Kagaku no Railgun Manga Chapter 088
  8. 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 8.12 8.13 8.14 Toaru Kagaku no Railgun Manga Chapter 087
  9. 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 Toaru Kagaku no Railgun Manga Chapter 094
  10. 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 Toaru Kagaku no Railgun Manga Chapter 095
  11. 11.00 11.01 11.02 11.03 11.04 11.05 11.06 11.07 11.08 11.09 11.10 11.11 11.12 11.13 11.14 11.15 11.16 Toaru Kagaku no Railgun T Episode 24
  12. Ogino Kentarou Twitter. Retrieved on 19 September 2020.
  13. 13.0 13.1 13.2 13.3 Toaru Kagaku no Railgun Manga Chapter 091
  14. 14.0 14.1 14.2 14.3 14.4 14.5 Toaru Kagaku no Railgun Manga Chapter 092
  15. 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 Toaru Kagaku no Railgun Manga Chapter 093
  16. 16.0 16.1 16.2 16.3 16.4 16.5 Toaru Kagaku no Railgun T Episode 23
  17. 17.00 17.01 17.02 17.03 17.04 17.05 17.06 17.07 17.08 17.09 17.10 Toaru Kagaku no Railgun T Episode 25
  18. 18.0 18.1 Toaru Kagaku no Railgun Manga Chapter 096
  19. Ogino Kentarou (Railgun editor), Twitter
  20. Toaru Kagaku no Railgun Manga Chapter 090


v  e
Dark Side of Academy City
Factions and Organizations Board of Directors (Board Chairman: FormerCurrent)
Kihara FamilyHound DogGROUPSCHOOLITEMMEMBERBLOCKFreshmenScavengerFull CourseSpark SignalDisciplinary ActionL.S.S.STUDY
Experiments and Projects Level 6 Experiments (Level 6 Shift Project) • Radio Noise Project (Third Season) • Agitate Halation ProjectClone DollyExterior ProjectDark May ProjectProduceFive OverRensaAnatomy Mechatronics
Total Human Cyborg Replacement ProjectWhite AlligatorChemicaloid Project
Aleister's Plan Windowless BuildingImaginary Number DistrictMisaka NetworkUnderlineDRAGON
Key Events (Timeline) Sisters Arc0930 IncidentSkill-Out UprisingBattle Royale ArcGemstone MiningDRAGON ArcWorld War IIIFreshmen ArcBaggage City ArcAgitate Halation ArcMental Out Arc
Other Magic-Science TreatyMilitaryDestroyerVoice on the Phone
See also: Academy City