Most people have a memory palace. A three-dimensional space within their psyche, which they can control to some degree. If they wanted to sketch something without looking at it, like an apple, they can conjure an apple into this space, and see some details they easily can copy with a pen and a restaurant napkin. A vaguely round shape, a little stem on top, maybe with a leaf on it, and a shiny part that kind of looks like a window.

Some, like Kyo Amano, who remember everything they’ve ever sensed in vivid detail, and have a several exabytes worth information they've learned from books and Internet browsing in their head, can create very complex memory palaces and completely immerse themselves in a world of their own imagination.

In Riko’s case she, like the majority of people, only experience that kind of immersion into their own psyche while dreaming. Which was what she was experiencing right now, sitting inside a classroom at her old high school, Nishimoto Chukosei.

It was one of those dreams where you were vaguely aware it was a dream, because Riko had the feeling she went to a different school now, called Tokyo Joshi Kagaku-Gijutsu Koko, and her friends from that school were in danger while she was here, sitting through some boring history lecture.

“It’s often asked, why don’t espers rise up, and establish themselves as a caste above normal people? There is an idea that has defined our society’s entire approach to this problem.” The teacher gazed across the classroom, fishing for student commentary. “Can anyone tell me what the Ultimatum Game is? How about you, Nomura-san?”

Riko shrugged. “One of those American superhero movies?” She looked away, resting her head on her palm. A few girls laughed at Riko’s foolishness, although they weren’t volunteering any answers either.

“I’d expect a less flippant answer from you, Nomura-san, given that your father’s papers on the topic helped popularize the idea in Japan. The Ultimatum Game is an experiment. Take two subjects. Give one of them the duty of dividing up ten thousand yen. The other subject has a decision to make. If he feels the split is fair, they both keep the money. If he chooses to reject the deal, neither of them get any money.”

“That’s silly,” Riko decided to shout out, since the spotlight was on her anyway. She’d love it if the teacher kicked her out of the classroom. She had the very strong feeling she was supposed to be somewhere else. “As long as they didn’t give you nothing, then why would you reject the deal? Seems pointless and lame.”

The teacher only seemed to expect this response, however. “The results from the experiment say otherwise, Nomura-san. Across numerous replication attempts, it has been found that if the second subject receives a share as low as two thousand yen, they are virtually guaranteed to wipe the table clean so that no one gets anything. Whereas when each subject receives five thousand yen, a fair, 50/50 split, they are pretty much guaranteed to accept the deal. The experiment has even been done with chimpanzees and food, although replication has been less reliable.”

Riko let out a loud, exaggerated sigh. She’d give rudeness one more try before she began throwing things to get booted from class. “What does that have to do with espers? You’re talking about monkeys dividing up bananas and stuff. I like monkeys, but I doubt monkeys are gonna be on the test. Tests are never that much fun.”

The teacher only smirked, and pushed his glasses up. Riko was furious. He was having way too much fun with such a boring subject. “It’s simple. Espers have the power. They decide whether they use their abilities to benefit everyone, and give all of humanity a 50/50 split, or try to rise above everyone else as samurai, aristocracy, Brahmin, or something of that nature. Giving those who weren’t born like them less than 20%. What happens if they do that?”

Some girl in the front raised her hand. 'Teacher’s little pet’, Riko grumbled under her breath.

“Normal people reject the deal.”

“That’s right. And when people reject the deal in real world politics, the results tend to be brutal and ugly. The French Revolution. The Bolshevik uprising. The Spanish Civil War. Dr. Yori Nomura didn’t want a future like that. That’s why he left a lucrative practice behind to enter politics. Isn’t that right, Nomura-san?”

Riko rolled her eyes. She was tired of being compared to her father. He was just some politician in the end. He did politician things, like making friends in the military-industrial complex and in big business, and she had the nagging sensation that she learned something about his shady past recently. She had to like the guy, because you only really get one dad, but that doesn’t mean everyone else has to like him.

“He believed if we helped espers share their gifts with the world, everyone would benefit. Everyone gets their five thousand yen, whether they’re esper or Normal.”

“That’s it!” shouted Riko victoriously. “I remember where I’m supposed to be now! I have to help beat up some wannabe samurai terrorists who are trying to take an eight thousand Yen split! One of them stuck me in this stupid classroom from the past!” She bolted to the door.

“Nomura, you’ve been warned about leaving without excusing yourself. You know you’re risking expulsion with your record of delinquency. Get back here!”

Riko yanked at the door handle, but the door didn’t seem to move at all. In fact, it seemed like the door was painted onto the walls. So were the windows. She was trapped here. The history teacher was her jailer.

Well, she knew one thing that has worked consistently on her problems today. Grappling them.

“Is your little outburst over, Nomura-san? If so, return to your seat right now- hey stop that!”

Nomura rushed him, pouncing the teacher and wrapping her arm around his neck, putting him in a lariat. Putting her weight into it, she managed to slam him into the ground. The figment of her imagination faded out, as did the rest of the students, and the classroom. She had weakened whatever was keeping her here.

The scene melted away into something else. She was inside… the cockpit of a giant robot? But the images on the dual view screens weren’t of a battlefield full of other giant robots, or a city being stomped on by a gargantuan reptile. She saw the Naka-Meguro Station platform. She saw a girl in orange, covered in scrapes and other wounds. And she saw Aimi-chan.

She remembered what happened. She had given Blue a warm, supportive hug. She thought she had gotten through to Blue, shown her that she didn't have to be Riko's enemy. Then Blue took over her body.

This was no giant robot, it was her own body! She was viewing things as if she had been shrunk down and stuffed inside her own head. She attempted to pull and poke at the controls. An error message flashed over the view screens: ‘MANUAL CONTROL DISABLED’.

Riko heard herself talking. Well, it was more like Blue’s voice, coming out of her own head. “Remember, if you attack me, you attack little Riko-chan. And if you hurt Dr. Nomura’s daughter, I bet you’d end up just like us. Hunted by the military. A pariah.”

Riko watched herself stride into the train. Her body walked up to one of the back cars, where a girl was sleeping. It looked like Blue, but human. She was wearing an unremarkable gray coat, long gray skirt, and gray shoes. She looked as though she made every effort not to stand out. Riko watched herself searching the sleeping girl’s coat

“Someone stole my laptop! All the JSDF data was on that thing! Was it some random jerk on the train? Or was it that teleporter? Hey Orange, we've got trouble!” The woman in orange walked towards where Riko’s body called out, approaching the train car. From the way Riko saw Aimi staring at her, she guessed she was the enemy, and Blue’s ally. The one called Orange had her back turned to Aimi. If Riko was gonna do something, now would be the best time, while the enemy was distracted.

Riko thought, "Wait, Blue-chan didn’t know how to possess people before, only trains and drones and stuff. Otherwise, she would have never let herself get taken prisoner, she would have possessed me right from the start. I felt Blue starting to change when I was thinking about how I wanted to support her. I didn’t realize Blue was gonna attack. What a jerk. I made ghosts turn solid twice today too, by thinking about defending my friends. Maybe I can give someone a power they don’t want? What kind of ability does Blue want least right now? Probably something to do with her leverage over Aimi-chan."

Riko filled her head with thoughts about how she wanted to support her beloved Aimi-chan, and to not be Blue-chan’s hostage. And she thought how much better things would be with a 50/50 split.

She grabbed a control stick, and jerked it forwards as hard as she could. And felt another change start to come over Blue.

The Brinsfield Abilities Primer has this to say about the Astral Projector ability known as Body Swap:

Astral Projection carries the risk that harm may come to the esper’s physical body while they are outside of it. Some Projectors develop the ability to trade bodies with their host, rather than merely hijack a single body, so that if something happens to their original body, they still have one to occupy, and they don’t suffer a final death.

This can be an especially frightening ability if used without consent to, say, repeatedly steal bodies and live forever, leaving the minds of their victims in their previous, decrepit body.

Riko opened her eyes. Well, not her own. Blue’s. She was wearing that gray coat. Hopefully, Blue wasn’t a total weakling.

“Hey Blue-chan! Give me back my damn body!” Riko said, as Blue, using her body to charge at her.

“Nomura? What the?” Blue replied, as Riko, the two of them tangling limbs and dropping to the floor of the train car.

“Alright that’s enough of that,” Orange shouted. She was almost into the car, when suddenly, her body decided to slam itself upwards into the ceiling of the train station platform. Behind where she once stood was an exceptionally angry looking Aimi.

“Aimi-chan my love! It’s me, Riko-chan!” shouted Blue's body, as Riko and Blue continued to grapple and flail at each other. Riko's mind was doing her best to keep her own body pinned down, but Riko was a well-fed girl, and now Blue's mind had control of that muscle and momentum.

Aimi replied flatly, “Yes.” Oh right, telepathy. That would save them some confusion.

Over on the other side of the platform, Nana Ishihara could be seen, spraying a gas pipe down with a fire extinguisher. A sizzle and a mouse-like death squeak could be heard. She seemed to be wearing Aimi’s jacket. Riko couldn’t help but be jealous. Above them, the metal ceiling that was keeping Orange from flying further into the sky suddenly gave way to a concentrated burst of flame from her boot, melting it wide open. The fiery esper was nowhere to be seen.

Now that Aimi-chan had done her part, it was time for Riko to show off her own power and deal with Blue once and for all. “Blue-chan?”

“What?”

“Riko-chan thinks Blue-chan has a really nice body. Riko-chan thinks Blue-chan shouldn’t hide it away from the world.” Leaning it up onto her knees, Riko made Blue’s body yank off that bulky gray coat as hastily as she could, tossing it aside, revealing the plain blue t-shirt she had on underneath.

“Stop it!”

Off went the t-shirt next, and Blue’s hands went to her own chest, where she was wearing a high quality bluish-gray bra. Squeeze squeeze. Riko, as Blue, let out an exaggerated gasp.

“Ohhh, very nice shape and size, Blue-chan. Blue-chan acts modest but Riko-chan is impressed! Blue-chan even has coordinated underwear. Does Blue-chan have matching panties too? RIko-chan would like to see!”

Riko’s body was blushing furiously. “Get off me!” screamed Blue, through Riko's body, flailing Riko’s arms against Blue’s body as Blue’s body straddled Riko’s 

Riko, as Blue, caught each of her own wrists, and brought her own hands up to Blue’s chest. “Does Blue-chan want to know what it’s like to feel herself up with Riko-chan’s hands? So naughty! Ooh, you’re going to make Aimi-chan mad, forcing skinship upon Riko-chan like this.”

Aimi was certainly glaring hard at the two of them, even if it wasn’t for the reason Riko said.

“No! No! No! No!” cried out Blue, as Riko, and in her frustration, a blue light suddenly began to shine that covered both Riko and Blue’s bodies. When it faded, Riko was in control of herself again. The body swap had been released.

If Blue hadn’t been so befuddled, she would have realized how easy this pin was to reverse. Riko put her hands on Blue’s shoulders, and shoved her down, laying herself on top of her. Blue continued to squirm against Riko’s weight until finally, she wore herself out, her body going slack as she passed out.

Riko got up and stumbled over towards Aimi. “We did it, Aimi-chan. We can go home now. Come on, we can get a taxi or bus or something.”

“No. They know who you are. They’ll figure out what school.we’re from. It’s not over.” Aimi rose up from the floor via psychokinetic flight, and bolted through the hole Orange left in the ceiling Riko was left alone upon the train station platform.

Nearby, she saw a bench, which had been ripped from its moorings and flung about, rise up and start to drift towards the ceiling hole, chasing after Aimi. Right now, it was hovering just low enough to the ground for Riko to jump on to. Maybe Riko could still fight by her beloved Aimi-chan’s side. She ran towards the flying bench, pushed from her legs as hard as she could, and arced through the air. When she crashed upon the bench's wooden surface, she clung on for dear life.

Whoosh! The bench took off through the ceiling. Below her, Riko could see the cityscape start to shrink, the sprawl of Tokyo expanding out. To her side was a trail of dark cloudy plumes, which she guessed were left by Orange, considering the bench was following them.

Looking up, she could see Aimi, hovering in the clouds, staring Orange down. Orange was glaring back  at her just as hard. Orange’s boot nozzles blazed brightly, spitting neon flames of pure psychokinetic energy.

The bench rose up besides Aimi, moving to guard her flank. Aimi glared hotly at Riko once she realized she was upon it. A normal person would have felt incredibly foolish to try to intervene in this kind of matchup.

But this was Riko we’re talking about. She did what she had to. Not what was smart.