"DOLLY" is the 68th chapter of the Toaru Kagaku no Railgun manga series. The chapter reveals the secret history of Kouzaku Mitori, her friendship with Dolly, and her eventual start of darkness.
The chapter was serialized in Dengeki Daioh as Chapter 70 but was renumbered for the tankōbon version due to Chapter 65 merging three magazine chapters into one.
As a young child, Mitori was an experimental subject in a research laboratory. She pretended to be obedient and polite to get on their good side. One day, she was asked to play with a strange girl called Dolly, to relieve the latter's stress. Mitori used her ability to entertain Dolly by creating moving liquid metal objects. While she initially wondered why she had to deal with someone she saw as stupid, Mitori warmed up to Dolly over time.
One fateful day Mitori came in as a check-up on Dolly was being conducted, and was shocked to see the machines embedded in her body. She is then told to leave the room by a researcher, who explains that the machines are for life support. Suspicious of this, Mitori began to investigate using her Liquid Shadow ability. Here, she discovers that Dolly is a prototype clone, intended for research in creating more long-lasting clones. She finds out that the researchers have been neglecting her health and giving her drugs to gather data, shortening her already short lifespan. Mitori confronts a researcher regarding this, threatens to go public with the information she gathered if they do not stop the medication on Dolly. The researcher refuses and tells her that the experiment was requested by the Board of Directors, pointing towards the Windowless Building. Mitori tries to attack him but is captured by two guards and placed alone in a room. The researchers decide to keep her alive as she will be useful to them once Exterior is complete.
A few months later, Mitori finds that the building has been abandoned and she is alone. She returns to the floor where she was shown the Windowless Building, swearing revenge.
Mitori planned and attempted an assassination attempt on the Board Chairman, but it failed and she was sent to the Reformatory. Sometime later, she was secretly removed from the Reformatory and brought before Kihara Gensei. There, he enticed her with the prospect of being able to gain the necessary power needed to annihilate Academy City. After he explaining his plan to her, Mitori asks him why she was chosen. Gensei explains that he only trusts those who are driven by hatred. From then on, she works for Kihara Gensei.
In the present time, Mitori wakes up after her defeat by Kuroko. Utterly beaten, she does not bother to remove her handcuffs with her power. Shokuhou Misaki appears and asks if Mitori was Dolly's former friend. She explains her own past with Dolly and tells her that there is a clone, Dolly's younger sister, who was implanted with the memories and experiences of Dolly. Misaki says that though this clone isn't Dolly, she just can't let her be, and tells Mitori to come with her. Mitori escapes her bonds and asks why she didn't just use her powers on her instead of explaining things to her. Misaki asks if she needed to use her power, to which Mitori says she didn't. Thus with a mutual understanding, Mitori stands once more to bring an end to the tragedy that has befallen on Dolly.
- Misaki reveals to Mitori that Dolly has a Sister in which all her memories and experiences have been transferred to.
In order of appearance:
No new characters were introduced during this chapter.
- Liquid Shadow - Kouzaku Mitori, Level 4 (for her present self; the Level of her younger self is unknown)
- Radio Noise (Electromaster) - Sisters (referenced-only)
- Mental Out - Shokuhou Misaki, Level 5 (referenced-only)
No new abilities were introduced in this chapter.
- Parameter List is referenced for the first time in a medium that is not the light novels.
- Endymion is showed for the first time in the Toaru Kagaku no Railgun manga. It was under construction.
- Misaki is shown passing by just before Mitori discovers Dolly naked.