Meeting Satoru was an overwhelming experience.
Rei was socially awkward by nature — the kind of person who calculated exactly how much he needed to say in a conversation to keep it from feeling uncomfortable, and almost always fell short. Gojo Satoru didn't give him space to calculate anything. He talked the entire way from the hospital to the apartment and from the apartment to the school, with the energy of someone who hadn't had an audience in hours, jumping from topic to topic with no apparent order while Megumi walked behind them with the expression of someone who had long since decided it wasn't worth trying to keep up.
Rei simply nodded at the moments that seemed to require a response and hoped it was enough.
Picking up Megumi was quick. The boy was investigating the area around the burned apartment, checking the perimeter with the quiet focus of someone who preferred facts over conversation. Gojo called out to him from a distance with far too much energy for the time of day. Megumi didn't seem surprised.
"This is Kagami Rei," said Gojo, pointing at Rei with the same finger that was holding a piece of candy. "He's coming to the school."
Megumi looked at him. Rei looked back. Neither of them said anything for a moment.
"Fushiguro Megumi," the boy said finally, with no more introduction than that.
"Kagami Rei," Rei responded, in exactly the same tone.
Gojo looked at the two of them with the expression of someone contemplating a work of art. "What a pair," he commented to no one in particular, and started walking.
Jujutsu High came into view around a bend, emerging between the trees with that specific stillness of places that exist just slightly outside the normal world.
Rei looked at it from the entrance for a second longer than necessary.
He knew it from his father's writings. Scattered descriptions, contextual references, names of people who studied or taught there. His father had described it as the center of the sorcery world in Tokyo — the place where everything converged, where sorcerers were trained and from where they went out to do what they did. On paper it had sounded almost mythical.
In person it was a school. A large school, with wide grounds and an architecture that mixed the traditional with something harder to name, but a school all the same. Rei wasn't sure whether that made it more or less intimidating.
"Megumi will show you your room. Tomorrow you'll meet the principal," was all Gojo mentioned before stepping away with the same casual energy with which he had appeared at the hospital — as though he had completed a task on his list and was already thinking about the next one.
Dealing with Megumi was easy, or at least easier than dealing with Gojo. He wasn't someone who talked more than necessary, and like Rei he was quiet by nature — not the uncomfortable silence of someone who doesn't know what to say, but the functional silence of someone who simply doesn't see the need to fill it. They limited themselves to introductions and Megumi telling him which room he'd be staying in.
Rei didn't have many belongings. A backpack with the few clothes he'd grabbed before leaving the apartment, a slightly old phone and its charger. He arranged them in the room in silence, stared at the ceiling for a moment, and slept better than he had in weeks.
The following morning Gojo knocked on his door before Rei had quite finished waking up.
"Good morning," he said from the other side, with the tone of someone who had been awake for a while and didn't understand why everyone else wasn't.
"Whenever you're ready."
Rei came out shortly after, dressed in a black shirt and loose trousers, his hair still somewhat disheveled. Gojo was waiting leaning against the hallway wall with his arms crossed and an expression that suggested he'd had something in mind since before he knocked.
He led him to an open space on the school grounds — a wide field, with level ground and enough distance from the buildings that anything that happened there wouldn't affect anything important. Rei looked at the space and mentally calculated how quickly he could get away if things went wrong.
The answer wasn't reassuring.
"Before you meet the principal, your cursed technique has me curious," Gojo commented, with the smile Rei was already learning to identify as the one that appeared when he was genuinely interested in something. "I'd like you to have a little training session with me."
He said it with the same ease with which someone might suggest grabbing coffee — with no apparent acknowledgment that he was asking a complete novice to go up against the strongest sorcerer of the modern era.
"Can I sue you if you break something?" asked Rei, unconsciously glancing down at his hands.
Gojo laughed a little. "You can try," he answered, without denying for a moment that he could in fact break something in the process.
They stood facing each other in the empty field. The morning was cold and quiet, the kind of silence that exists just before something interrupts it. Rei breathed slowly and covered his body with cursed energy — the energy responded instantly, wrapping around him with a familiarity that still felt strange, like putting on clothes he didn't remember buying but that fit perfectly.
He took a step forward — and ceased to exist at that point in space. He came back into existence right beside Gojo, his fist already in motion. Ever since he'd discovered that ability it had been his favorite — the element of surprise made it work almost every time. The problem was that his current target was Gojo Satoru.
Rei felt how his punch never arrived. It wasn't blocked — it simply didn't arrive, as though the space between his fist and Gojo were longer than it should be, infinitely longer.
"Let me explain my technique," said Gojo, turning toward Rei with complete calm, ignoring the attempted attack the way one ignores a fly. "Limitless allows me to control the space around me at an atomic level." The characteristic smile. "The barrier surrounding me is infinity — it slows down infinitely anything that tries to come near me."
Rei processed that. He remembered reading about it in his father's notes, though on paper the technique had sounded abstract. Seeing it in practice — or more precisely, not being able to see it in practice because that was precisely the point — was different.
He also remembered the binding vow. Explaining a technique temporarily enhanced it during combat. Though Gojo probably didn't need that advantage at all.
He took two steps back. "Paradox," he said.
Gojo tilted his head, genuinely attentive in a way that was different from his usual casual attention.
Rei paused. The words weren't coming out in the right order. "My technique creates paradoxes," he said slowly, like someone discovering what they think as they say it out loud. "I still don't know how to explain it properly." Another pause. "I can exist in more than one place at the same time. Land hits I never threw.
Things that shouldn't be able to happen simultaneously — happen." He stopped. "That's roughly it."
He was really bad at explaining it. Gojo couldn't help but be reminded of Shoko trying to explain reverse cursed technique — though nobody was as bad as Shoko at explaining things. Thanks to his Six Eyes, Gojo had already deduced the nature of Rei's technique. If his ability to create paradoxes was properly trained, he could become incredibly powerful — and that, combined with his enormous amount of cursed energy, genuinely excited him on the inside.
Rei simply stared at Gojo for a moment, something seeming to click. Despite being an abstract concept he decided to put it to the test. Gojo's Infinity was itself a paradox — an object approaching another that can never quite reach it. And if Infinity was a paradox, then Paradox should be able to interact with it somehow.
The problem was movement.
Until now, everything Rei had done with his technique had involved movement in some form. When he appeared beside someone, his body was still traveling — just in a way that reality couldn't track properly. When his hits came from impossible angles, they were still blows that departed from one point and arrived at another. There was a trajectory, even if it was a paradoxical one. And Infinity, ultimately, could process anything that had an origin and a destination — because between origin and destination there was always a distance to subdivide.
The question was what happened with something that had neither.
Not a punch that traveled fast. Not a punch that traveled impossibly. A punch that simply existed directly at the point of impact — without having come from anywhere, without having covered any distance, without giving Infinity anything to process.
A pure paradox of position. A fist that didn't move because it had never been anywhere else.
Rei didn't know anything about quantum physics. He didn't know that what he was attempting had a name — that physicists had spent decades discussing particles that existed in a superposition of states until observed, present in all their possible states simultaneously until something collapsed that superposition into just one. He only knew that his technique allowed him to create paradoxes, and that a fist that existed simultaneously here and at the point of impact without crossing the space between them was, by definition, exactly that.
His fist didn't travel. It didn't move. It didn't disappear from one place to appear in another. It simply existed directly at Gojo's shoulder — as though it had always been there and reality had just decided to acknowledge it.
The hit landed.
It wasn't strong — Rei didn't have enough control to concentrate real force into something he still didn't fully understand. But it landed. Rei's hand touched Gojo's shoulder with a solidity that shouldn't have been possible, and for an instant the field went completely silent.
Gojo didn't move. He looked down at his shoulder slowly, then looked back at Rei with an expression Rei hadn't seen on him until that moment — not exactly surprise, because Gojo Satoru didn't get surprised, but something closer to genuine recognition. Like someone who had just seen something they had been waiting for without knowing they were waiting for it.
"Interesting." He said it quietly, almost to himself. Then he smiled. "Your punch didn't happen."
Rei looked at him. "No."
"Infinity can only stop what has an origin and a destination — something that departs from one point and heads toward another." Gojo scratched the back of his neck with a thoughtful expression, like a teacher who had just found a problem he liked. "Yours had neither. It didn't come from anywhere. It was simply there."
A pause. "Did you know you could do that?"
Rei took a moment to answer. "Not exactly."
Gojo looked at him for a second. Then he laughed — not the performative laugh from before, but something more genuine and shorter. "You've been doing this alone for a week and you already found a gap in Infinity." He shook his head slightly, still smiling. "I definitely made the right call last night."
Rei said nothing. He was processing — not the hit itself, but the understanding that came with it. The difference between what he had done before and what he had just done was the difference between moving in ways no one could track and not moving at all. His technique didn't work by moving things in impossible ways. It worked by eliminating the need for things to actually occur, leaving only the result.
The next thing Rei knew he was on the ground staring at the morning sky, his stomach protesting in a way that would have been considerably worse if he had eaten anything before leaving his room.
Gojo, visibly more animated than he had been at any point during the training, still had the energy of Blue dissipating from his fingers. "Yuta and Hakari went through the same thing," he commented with total calm, reaching into his candy bag. "You get used to it."
Rei didn't respond. He was too busy making a mental note that someday he was going to pay that back.