Chapter 10 of Toaru Kagaku no Railgun Gaiden: Astral Buddy was released on March 27th 2018.
As Iruka's accomplice wonders how the card of Misaki's head could have fallen off, she reveals the true nature of the card on her hand. It is a card that uses the principles of the Indian Poker to transform the user's brain as a monster who is true to their desire, an evil hypnotism card. Though the girl doesn't really care for the technical stuff as she is merely fulfilling her duty. Meanwhile, the Ghost girl is sinking into a sea of memories wondering if it is still Misaki's.
Then the story unfolds to a memory of a time long ago. It is a young Iruka being hugged by a couple of girls as she enters a room. Suddenly, a phone's button is pressed and the girls are forced away from her. The girl that used her powers apologize to Iruka for their behavior as they are only looking forward to making new friends. They are introduced to each other and the girl's name is revealed to be Mitsuari Ayu. Ayu wonders where's the other visitor as she was told there would be two. At the threshold is a little girl with twintails crying out for Iruka. Iruka approaches and tries to console her. Ayu asks if she is her little sister, to which Iruka says that she is the younger sister while the crybaby, Yumiya Rakko, is the older one. Hearing their names, Ayu notes that she has an animal name as well, which in this case is an insect: an ant. Ayu then welcomes them to Ideal.
As the girls look around the facility, Iruka notices a girl in braids all alone: it is a young Hokaze Junko. She tries to introduce herself to Junko but she tells her not to come closer as she brings people harm. Suddenly, Junko is in pain and holds her head in pain, trying to calm down. She staggers and falls on the wall, cracking it. However, Junko is unhurt, remarking in dismay that she "did it again". Iruka is surprised by this, to which Ayu says that it happens all the time, much to Iruka's surprised. Iruka points out that Junko was holding her head, to which Ayu says that it was because Junko was the most affected by her powers, but because of it she was able to grow from a Level 2 to a Level 4 in only two months, a feat the teachers said they have never seen. It is the reason why, Ayu says, why everyone looks up to Hokaze Junko.
Meanwhile in the System Scan room, Junko punches a punching machine, and sends it flying to the wall behind it, cracking it from the impact. The researchers remark on how that the machine was built to survive impact from a large semi truck. One of them remarks that Junko's output may be that of a Level 5, which amazes Iruka. Ayu says that the facility is special since it actually raised a Level 5, though it's a secret. Ayu remarks how only the elite are allowed in this special education facility as it has the ability to create a Level 5. Ayu then says that if Iruka works hard here and she too can become a Level 5. Iruka then becomes excited after hearing this, believing that she can become like Junko someday.
Back with Junko, apparently the pain has finally gotten to her and she falls to the floor panting. But then, a young Misaki comes over to her, and reprimands her. Junko acknowledges her, saying that she has already told her to go away, though Misaki points out that it's because she runs away every time she says it. As she struggles on the floor, Misaki touches her forehead on Junko's, and then as she uses her powers to connect to her, Misaki is assaulted with throbbing pain. Misaki discovers that Junko is somehow able to endure a cluster headache and wonders how she had kept her sanity. Misaki thinks she could restrain it by using her brainwashing ability though is wary as she couldn't read any abnormality in the affected area. Despite this, Misaki risks it and syncs up with her, and with a touch of her remote the pain is all gone. All the pain Junko has gone through is gone, as Misaki leaves. Junko asks how she could repay her, to which Misaki says that she just owe her one. As she leaves, Junko wonders what her name was as she never told her.
In Misaki's thoughts however, she has become weary of the facility. Despite not wanting to be involved with anything outside of the Exterior Project but when she saw Junko, she couldn't just ignore her and ended up helping her. Misaki is wary of the way things are being run to create espers as if the researchers are doing something else alongside it. Misaki wonders what Clone Dolly, a facility meant to mass-produce geniuses, wants badly to create enough for them to warrant in destroying so many espers. Despite this, Misaki washes her hands of the matter.
Meanwhile, Ghost Girl sees all of the events transpiring before her. She wonders how she is able to see both Misaki's memories and events where she wasn't involved in, and wonders if it was Iruka's memories. Ghost Girl hypothesizes that it was because Iruka kissed Misaki causing moisture contact, which pulled out matching memories like some sort of Psychometry. As the Ghost Girl scrambles her brain over this, she suddenly realizes that she is up near the ceiling. Since she is only peaking in on memories, it would mean someone saw the scene from the ceiling, who was neither Misaki nor Iruka. With that, Ghost Girl wonders whose memories is she peaking into.
Somewhere, a little girl wakes up and a researcher monitoring her welcomes her back. The girl relates how she "went" to all sorts of places again which was fun for her. With that, their session is over, and the researcher says farewell, saying they'll see each other tomorrow. After she left, the little girl remarks how "Misaki-chan" is nice.
- The ghost girl sees the circumstances of Hokaze Junko and Shokuhou Misaki's first meeting in a memory.
By order of appearance:
- Rampage Dress - Hokaze Junko, Level 4.
- Mental Out - Shokuhou Misaki
- Mental Stinger - Mitsuari Ayu
- Psychometry (referenced)
- This chapter confirms that the Indian Poker card affecting Misaki was the malicious one that she was weary of.
- This chapter confirms the blood relationship between Yumiya Iruka and Yumiya Rakko; they are siblings with the former being the younger while the latter is the elder one.
- The flashback shows that Misaki didn't take over all of Clone Dolly, just those involved with the Exterior Project.
- Junko, Rakko, Iruka, and Ayu's past in Clone Dolly, a facility first referenced in the third Toaru Majutsu no Index light novel and explored in Chapter 60 of Toaru Kagaku no Railgun is shown here.
- The experiments on Junko gave her cluster headaches, an illness that is said to be one of the most painful and is known as suicide headaches.
- Who is the Level 5 that Ayu said that Ideal was able to raise?
- What exactly is the other purpose of Clone Dolly other than to raise espers enough for them to warrant destroying excellent espers?
- Is the girl shown at the end the ghost's true identity?
- Mitsuari Ayu: "This is the Clone Dolly 3rd lab: Ideal. Work hard here, and you too can become... a Level 5."--said to Iruka.