"Cooperation" (連携 Renkei?) is the 54th chapter of the Toaru Kagaku no Railgun manga series.
Using Uiharu Kazari as a hostage, Kouzaku Mitori orders Misaka Mikoto to end the call on her phone and get rid of her. Mikoto ends the call and discards her phone. Mitori then talks about how Mikoto attacked her group's villas and stole information, which confuses Mikoto as she never did this. Mitori asks where the Sisters are being hidden. Mikoto refuses to answer and responds with her own question: why is Mitori's group attacking Mikoto's friends? Mitori claims that Mikoto is odd for being able to live like a normal student despite knowing about Academy City's dark side. Mikoto still refuses to answer and orders Mitori to let Uiharu go. This causes Mitori to reveal that she (using what appears to be a duplicate of herself) has also taken Mikoto's mother Misuzu hostage. Mitori asks for the Sisters' whereabouts again, saying that even the #3 Level 5 can't rescue both hostages at once. Mikoto refuses a final time, saying that she will save Uiharu even if it costs her own life. She uses magnetism to attract Uiharu's metal seat and also to intercept Mitori's knife with her own phone, then closes in to electrocute Mitori. The second Mitori prepares to kill the unconscious Misuzu, but Shirai Kuroko teleports in and drops her wheelchair on Mitori. Mitori dodges and throws a knife at Kuroko, who teleports away with Misuzu. Kuroko checks to confirm Misuzu is unharmed, which allows Mitori to escape.
She then teleports over to the first Mitori with the intention of interrogating her. "Mitori" thrusts a bladed tentacle at Kuroko, who teleports away but gets her hair cut in the process. "Mitori" stands to reveal that it was actually an inhuman puppet wearing a disguise. Kuroko tries teleporting darts into the puppet but this proves ineffective. Mikoto orders Kuroko to teleport the hostages away and considers using her Railgun. The puppet points at Mikoto, smiles, then falls apart into a puddle of liquid. Inspecting the liquid, Mikoto and Kuroko conclude that it is liquid metal that was being remotely controlled via an esper ability.
Mitori walks through the sewers. She recalls that Mikoto denied attacking MEMBER's villas, from which she deduces that the witnesses either lied about Mikoto being responsible or had their memories altered. She also recalls that Mikoto looked angry when she mentioned the city's dark side, and thinks that there seems to be hope left for something.
Kuroko asks Mikoto to tell her what's going on, having figured out that Mikoto's statement (that she would save Uiharu) was intended to tell Kuroko to save Misuzu. Mikoto explains that she sensed Saten calling her phone and deduced that Kuroko would come over to investigate. She also explains that her mother would have gotten angry if Mikoto had chosen her over a friend, and she trusted Kuroko to protect her mother. Embarrassed, Kuroko protests that she only did her duty, then feels pain in her leg. Mikoto apologises for making her force herself despite her injury and helps her to walk. Kuroko tells her to let go and claims she doesn't have that kind of (sexual) orientation.
After taking Uiharu and Misuzu to receive care, Mikoto and her friends sit down to talk. Mikoto confirms that the girl seen in the memories of Misaka 10032's cat is Shokuhou Misaki. Saten Ruiko then brings up the phrase "Auribus oculi fideliores sunt": it has the same name as an urban legend website; Uiharu was unable to find that site the previous day; Saten searched for that site just now but couldn't find it due to many identical pages hiding it. They deduce that the site has information that Misaki wants to keep hidden, Misaki controlled Uiharu to delete the data, and she discovered that Uiharu was Mikoto's friend while examining her memories. They decide to follow this line of inquiry further.
In order of appearance:
- Kouzaku Mitori
- Misaka Mikoto
- Uiharu Kazari
- Heaven Canceller (cameo)
- Misaka Misuzu
- Shirai Kuroko
- Saten Ruiko
- Shokuhou Misaki
- Electromaster (Railgun-variant) - Misaka Mikoto, Level 5
- Teleport - Shirai Kuroko, Level 4
- Mental Out - Shokuhou Misaki, Level 5
- Liquid Shadow - Kouzaku Mitori, Level 4
- Mikoto's and Kuroko's encounter with a rock doll on the first day of the school term is mentioned. This refers to their encounter with Ellis, Sherry Cromwell's golem, during the events of Toaru Majutsu no Index Light Novel Volume 06.