"Dark Side" (暗部 Anbu?) is the 52nd chapter of the Toaru Kagaku no Railgun manga series.
Wannai Kinuho manages to destroy all of the Type: Great Dane robots, but expends all of her water in the process. Baba Yoshio praises her achievement, since he had calculated that she would run out of strength with two robots left, but asks what she will do now. Kinuho says that she has received self-defense training as a Tokiwadai student and is prepared to fight without her powers. Baba simply calls out more robots that he'd kept in reserve.
Meanwhile, Awatsuki Maaya chases another robot carrying a case (which may or may not contain the nanodevice she needs to treat Kongou Mitsuko's paralysis), thinking to herself that she needs to hurry. She takes a shortcut by running across water, allowing her to catch up to the robot and retrieve the case. She sees lots of debris and realises that they've now come to the place where Kongou was fighting before. The robot attacks, but Maaya stops it by making it float and then lifts a massive chunk of debris with one hand. She jokes about having superhuman strength.
Going back to Kinuho and Baba, the latter explains how he's seen through the former's powers. Confident in his victory, Baba orders his robots to attack. Kinuho then reveals that there are underground drains in the park, pulls water out of one such drain and uses this water to surround Baba's head. Kinuho explains that Baba had miscalculated: she can control four clumps of water at once, not three. Panicking, Baba orders his robots to suck away the water, which allows Kinuho to destroy them all. Baba uses his last resort, sending out a Type: Mosquito robot in an attempt to paralyse Kinuho. He also tries to stall for time by talking. However, the Type: Mosquito becomes unable to fly when it approaches Kinuho. Maaya arrives, explaining that the case she found was empty so she figured that Baba must have the Type: Mosquito, and he would try using it if he lost so she (Maaya) reduced the buoyancy of Kinuho's surroundings. Maaya also steals Baba's case in the process. Desperate, Baba tries talking his way out of the situation. Kinuho slaps him and suggests that he try to accept other people. Baba runs away. Kinuho wonders if it was presumptuous of her to say such things, but Maaya believes that these words had to be said for Baba's sake.
Baba flees back to his base, refusing to accept his loss. He unleashes his powerful Type: Mantis robot, planning to take revenge by destroying the girls physically, mentally and socially. He then sees the GPS signal from the Type: Mosquito approaching the Type: Mantis. It is actually Misaka Mikoto (who is carrying the nanodevice, having retrieved it in the previous chapter). Baba thinks that it can't be Mikoto as she should be paralysed (not knowing that he'd mixed up Mikoto with Misaka 10032) and thinks that this must be a Sister. He orders the Type: Mantis to capture her, thinking to redeem himself with this achievement, but Mikoto easily destroys it. Mikoto tells Baba (via the Type: Mantis' communications equipment, which she had left intact) that she knows his location, says she'll let him go since he's being controlled by Shokuhou Misaki (not knowing that he works for MEMBER and has nothing to do with Misaki), but warns him that she'll crush him if she sees his robots near her friends again. Baba faints.
Elsewhere, Kouzaku Mitori receives a message from Baba: all of his robots have been destroyed, he wants a safe place to hide, and Misaka Mikoto has not been successfully stopped. Mitori decides that she needs to head out. Xochitl warns that Mikoto is strong, but Mitori claims that she doesn't need to defeat her and cleaning everything up within the day should be sufficient.
By order of appearance:
- Hydro Hand - Wannai Kinuho, Level 3
- Float Dial - Awatsuki Maaya, Level 3
- Electromaster (Railgun-variant) - Misaka Mikoto, Level 5
- Xochitl references seeing Mikoto fight at close range before. This happened in Toaru Kagaku no Railgun SS: Liberal Arts City.
- What are MEMBER's plans for Mikoto and the Sisters?