Touma and Misaka Imouto picked up a black together, with the former visiting a bookstore in order to find a book on how to look after a cat. While Touma is in the store, Misaka Imouto is outside looking after the cat, however, the cat begins trembling as a black figure approaches and Misaka Imouto leaves it behind as she deals with. Touma returns to find that she is gone and only the cat remains, and there, he goes towards a suspicious narrow back alley to a familiar leather shoe, and then finally, he finds a figure of a girl in the uniform of Tokiwadai Middle School—Misaka Imouto collapsed on the ground in a pool of her own blood. Touma reports the incident, and when he is asked to revisit the scene, the body is gone, no traces can be found, not even the blood or the leather shoe. However, Touma later finds something in his peripheral vision an impossibility, it is Misaka Imouto carrying a body bag and many other Misaka Imoutos.
In the shadows of the alleyways runs Mikoto's sister. She is breathing heavily, while carrying gun and wearing her goggles that glows a tealish color. She keeps on running, even when one of her shoes has fallen off; she removes her other shoe as so she can run properly. Suddenly, a voice is heard speaking. It is the voice of her tormentor, Accelerator. He asks her why she is running, and taunts her on how she is flashing herself to him. Mikoto's sister stops and fire several bullets towards him, seemingly hitting Accelerator. Suddenly, the bullets fly back towards her, and one of them hits her right shoulder. The force of the impact collapses her to the ground. Accelerator is still alive, unharmed. He comes closer to her and asks her what exactly he is doing. He leans forward; however, the girl fires her gun to his face. Strangely, the bullets stops in midair, and is redirected to her. Thinking quickly, she shields herself with her gun, and throws it towards him immediately after, though destroying her gun. She runs away, putting a little distance between her and Accelerator. She attacks him with her electric powers, however, it does not work and Mikoto's sister gets electrocuted by her own powers. She collapses and breaks several glass bottles near her; even in pain she realizes what Accelerator's powers is, "Reflection". Accelerator quickly says that she is incorrect, and that his power is "Vector change". He enumerates a list of things that he can control and tells her that anything that has vectors can be changed by him with a touch, and states that his power is set to reflect by default. Accelerator leans down and touches the open wound of Mikoto's sister. Accelerator tells her that he is now touching her blood, and asks her quizzically on what would happen to the human body if the direction of the blood flow is reversed. He smiles widely and tells her that if she answers correctly she will be given a peaceful rest, to her horror.
Meanwhile, Touma finally comes out of the bookstore, wondering where Mikoto's sister is. He notices her black cat on the ground and picks it up. While wondering where she is Touma feels an eerie foreboding in a certain alleyway. Touma investigates the alleyway due to this feeling; here, he finds that there seems to be nobody there, however, his feelings of dread push him onwards deeper into the gaping darkness. There, in the darkness he finds a lone bloody shoe, probably worn by schoolgirl. Touma looks forward and sees several bullets as well as a bloody shoe that seemed to be the part of the pair he just found. He walks forward, and passes by what he had discovered. Touma finds a fork in the path and turns left, he keeps on walking under the color of darkness, and there in his sight lies a girl he was looking for, the girl he was just talking to a while earlier, that girl was in her own pool of blood, that girl is Mikoto's sister.
Touma is completely horrified by what he has seen, he steps back a few times seemingly unable to take in what has occurred. He shakes and falls to his knees, where he is induced to vomiting.
The scene cuts to several Anti-Skill members guarding a certain location away from bystanders. We see Touma sitting on the ground in despair, still with the cat that he had left with the girl that has now died. One of the Anti-Skill members approaches him and asks if Touma could come with them to the scene of the crime. Touma obliges and escorts two Anti-Skill members to the scene of the crime. Touma is still in a daze to what happened, he passes by the shoe he saw earlier and becomes irritated because of it. They finally reach the supposed scene of the crime, but to Touma's bewilderment not a drop of blood can be found. Confused as to what happened, he runs towards the spot where he saw Mikoto's sister lying in her own blood. The Anti-Skills asks him if there is something wrong, to which Touma says that the body was supposed to be here on where he stands, this prompts to search for any clues as to where the body is. However, they find nothing however, Touma is still convinced that Mikoto's sister died in the place where they are standing. Suddenly, the cat notices something; Touma feels something off as well and runs toward this feeling, leaving the Anti-Skills behind.
Touma keeps on running into the darkness, following his intuition, determined to find the answer. He traverses a considerable distance, and in the distance sees in the darkness the familiar glow of Mikoto's sister's goggles. Touma stops and looks at the person before confirming that she is truly alive, who at the moment is carrying a rather large bag, big enough to fit a person inside. Touma is stunned, and asks how it is possible that she is still alive. The girl before him speaks, and asks for forgiveness for leaving him, she states that her intention was to return to him after the operation was over. Touma stops her to catch his breath, he says that he really thought that she was truly dead back there and is relieved that she is alive. However, the sister corrects him, stating that she has truly died. Shocked by her statement, Touma asks what she is carrying the bag. The sister doesn't answers him, but demands Touma to decode a series of letters and numbers, seemingly a password. Touma does not what is happening and as such the sister tells him that Touma is not part of the experiment. Touma tries to figure out the contents of her bag, however, he suddenly hears a familiar voice from behind her.
She looks like Mikoto and the girl that is standing before Touma which surprises, this girl talks of "Sisters", and another similar looking girl talks on how she is apologizing for leaving the cat behind. Another one appears and says that the reason for her actions is because she did not want to involve an animal in their conflict. Another one appears apologizing for worrying him. Another one appears and another one, the Mikoto sister that was carrying the bag tells Touma that every one of them is Misaka. Touma is surrounded by Misaka Mikoto look-alikes and is thoroughly confused. The Misaka look-alike that was carrying the bag began to speak, she calls herself Misaka 10032, and tells Touma that she was the one Touma was interacting with all this time. She explains to Touma on how they use their electric abilities to link their similar brainwaves together as so they can share their memories, she explains that the other Misaka's simply share Misaka 10032's memories. Touma asks who she is which she replies that they are mass produced clones for military use, that were created from the DNA map of the 3rd level 5 of Academy City, Misaka Mikoto; she calls themselves Sisters. Touma asks what they are doing to which she replies that they are simply doing an experiment, though she is not allowed to explain the details of it. Misaka 10032 apologizes once more for involving Touma in their experiment. Having finished their business, the clones leave one-by-one, with Misaka 10032 asking Touma to take care of the cat for her.
With the information he has learned from the clones, Touma wonders if Mikoto knew what was going on.
Meanwhile, back in the Tsukuyomi Residence, Komoe and Aisa are having dinner while telling ghost stories. Komoe mentions that she won't be afraid of any stories regarding the seven mysteries of Academy City; however, Aisa tells a story regarding the char on the meat that they are cooking, leads to cancer, which scares Komoe a little. They hear a doorbell and Aisa goes to see who it is. She opens the door and sees Index lying on the ground saying that she is hungry, which Aisa quickly closes. However, Index knocks on the door forcing Aisa to open it, here, Index asks Aisa to feed Sphynx at least, making Aisa sigh. Index is later seen eating the meat that they are cooking, she says that Touma hasn't come home yet, and thus she thought she was going to starve. Komoe later presents a yakiniku set, which excites Index and aggravates Aisa at her enthusiasm.
Back with Touma, he is currently riding on a bus heading for the Tokiwadai Middle School Dormitory. The bus announces that it has arrived in its intended destination, and stops. Touma steps out of the bus and heads into the Tokiwadai Middle School dormitory, here, he sees that there is no one inside the main entrance, but discovers a panel with buttons on it as well as the room numbers for the students. Touma discovers that Mikoto resides in room 208, and decides to use the panel to contact her. Touma wonders what he is supposed to say when he sees her, asking himself if he is going to ask her about the experiments, however, he resolves to still contact her. Touma successfully connects to Mikoto's room, and tells the receiver his name. The voice tells Touma that she is her "Oneesama's" roommate and not to worry about bothering her. However, Touma notices that he has heard that voice somewhere, suddenly the receiver as well notices the familiarity of Touma's voice, and hysterically remembers that he is the one that rendezvoused with Mikoto just this morning. She asks Touma what he wants with Mikoto, and with Touma replying that it is not something major. The voice complains on how he has suspiciously gone all the way here to search for Mikoto for something that is not major. The voice calms down and opens an electronic lock, the voice says that Mikoto has not come home yet but he is allowed to wait inside their room.
Touma walks towards room 208 of the Tokiwadai Middle School Dormitory and knocks on its door. The voice from earlier says that he is allowed to open it and come in as the door is not locked. Touma comes in and discovers that the voice belongs to the girl she met earlier, Shirai Kuroko. She confirms that Touma is the one who she is talking to and asks him if something happened between him and Mikoto. Which Touma quickly denies, to which Kuroko agrees, saying that Touma looks like he wouldn't talk of such steamy subjects. Kuroko allows Touma to sit on her bed instead of standing, to which Touma asks what she is doing on Mikoto's bed, and asks if she is a pervert. Kuroko takes insult to that and proclaims that there are things that are acceptable inside their hearts, like playing the recorder belonging to girl you like or stealing her bike saddle. Touma quickly states that he doesn't do that and asks himself if this is the true state of rich girls' schools. Touma asks why she is roommates with Mikoto even though she calls her Oneesama. Kuroko states that she is truly Mikoto's underclassman and says that she moved Mikoto's former roommate out in a legal fashion. Kuroko keeps on talking, saying that Mikoto has a lot of enemies as is the fate of those who hold powers, and calls the previous roommate of Mikoto's a traitor. Kuroko then asks if Touma was the one who quarrels with Mikoto all the time; however, Touma doesn't what she is talking about which prompts Kuroko to apologize if she was mistaken, as she just wanted to see the face of the one who was giving Mikoto support.
Suddenly, footsteps can be heard from the hallway outside, Touma thinks it's Mikoto, however, Kuroko know who it is, the Tokiwadai Dorm Supervisor. Kuroko becomes worried of having her find out that Touma is inside their room. With no choice left, Kuroko touches Touma's shoulder and tries to teleport him outside; however, she discovers that her power does not work on him. Touma tries to explain that it is because of his right hand, which Kuroko grabs and forces his body under Mikoto's bed to hide him while Kuroko go deal with the supervisor.
Under the bed Touma discovers documents stuffed inside Mikoto's giant stuffed bear doll, Kirugumar. Here, he discovers that the document he acquired contains important information on the sisters. Touma reads that the Tree Diagram calculated that only Accelerator, the strongest level 5 of Academy City can attain level 6. By preparing battlefields and fighting according to scenario, Accelerator's growth into a level 6 will be stimulated by the battlefield. Touma turns a page and discovers a map on it, discovering several crossed-out points on it.
This is wrong, Touma said to himself as he runs through the streets of Academy City's night time air. He is searching for one girl alone, Misaka Mikoto, as she is the key to the madness that is occurring with her sisters. Touma however suddenly stops after noticing something. He sees that the propellers of the wind turbines are moving even though there are no winds tonight. Touma concludes that since the wind turbines produce electrical energy due to the turning of its propellers, inversely the propellers can be turned as well if electrical energy is fed into it. Touma concludes that following the turbines will lead to her, to Mikoto, a level 5 electromaster who produces electrical energy every second.
Meanwhile, Mikoto stands alone with a determined look upon her face, looking at the sky.
- Accelerator and Misaka 10031's battle concludes with Accelerator killing Misaka 10031.
- Touma discovers the existence of Sister clones, as well as their usage in the Level 6 Shift experiment.
By order of appearance
- Misaka 10031 (not referred to by name)
- Kamijou Touma
- Misaka 10032's cat
- Misaka 10032
- Tsukuyomi Komoe
- Himegami Aisa
- Shirai Kuroko
- Misaka Mikoto
- Other Misaka clones
- Tokiwadai Dorm Supervisor (partial body and voice)
- Accelerator (Ability) - Accelerator, level 5
- Electrical attacks - Misaka 10031, level 3
- Teleportation - Shirai Kuroko, level 4
- Imagine Breaker - Kamijou Touma, level 0
- Radio Noise - Misaka clones
- The book that Touma bought from the bookstore is left behind in the sidewalk after escorting the Anti-Skill members. This is also the 2nd time Anti-Skill is featured, last time being in episode 2.
- This is the first episode we see Aisa living with Komoe. This episode also features Komoe drinking beer in actuality.
- Komoe mentions for the Seven Mysteries of Academy City in this episode, which is ironic since Komoe is considered one of the mysteries in the novel.
- This episode confirms that teleporting Touma will not work.
- First appearance of Kirugumar
- AIM is not directly mentioned, however, its characterstics are used by Touma to find Mikoto.
- Tarpaulin covers Komoe's ceiling which is a reference to Index destroying its roof back in episode 06.
- Kuroko references her meeting Touma from the previous episode, as well as Mikoto's constant quarrels with him such as from episode 1.
- Misaka 10031 uses a FN F2000 in her fight against Accelerator, which is a fully-automatic bull-up assault rifle. Despite it's bulky size, it only weighs 3.6 kilos.
- Despite what Accelerator said to Misaka 10031 about his powers, heat is not a vector but a scalar. Which means that Accelerator's powers may encompass scalars as well. However, if one logically looks at heat, it is the vibration of molecules, which means matter moving back and forth. This means that he could be controling heat indirectly though the vectors of the molecules themselves, but this is unconfirmed as the extent of Accelerator's powers and how exactly it can redirect vectors of even minute objects has not been shown.
- What Komoe, Aisa, and Index are cooking in Komoe's apartment is called a Yakiniku, which literally means "grilled meat".
- Touma's eyes become off-model during the scene where he realized that Misaka 10031's body went missing.
- During Touma's bus trip to the Tokiwadai Dormitory, the first reflection we see of Touma's body has him missing a part of his neck on the reflection after the mettalic part of the window cuts of the reflection of his face. The next reflection however, shows Touma's reflection normally.
- Why was Accelerator the only one that can obtain level 6?
- How did Kuroko end up as Mikoto's roommate?
- How did Mikoto obtain those documents?
- What did those crosses on the map Touma found inside Mikoto's stuffed bear mean?
- Accelerator: "Sorry, that's not quite the true nature of my skill. The answer is 'vector change'. Momentum, heat, electric charge. All kinds of vectors can be changed with just the touch of my skin." -Accelerator revealing his powers to Misaka 10031.
- Accelerator: "Now, time for the consolation prize question. I am now touching the flow of blood. If I reversed the direction of the flow, what would happen to a human's body? A correct answer and you will be given a peaceful...slumber." -said to Misaka 10031 before killing her.
- Misaka 10032: ""Misaka did actually die," reports Misaka." -Misaka 10032, confirming Touma's suspicions.
- Touma: "If I see her, then what? Am I going to ask about the details of a horrifying experiment where people get killed easily?"
- Kuroko: "And, you must be the gentleman that has been quarreling with Oneesama frequently, right? Forgive me if I'm mistaken. I simply wanted to see the face of the one that has been giving Oneesama support." -said to Touma.