When he finally managed to get back on his feet, the time came for Rei to meet Principal Yaga in person.
He already had an idea of his personality. His father's writings mentioned him briefly but with enough detail to form an impression — that of a man too principled for the world he lived in, someone who had chosen to see beyond what was expected of him. He had managed to bring hope to a desperate person when they needed it most, using his technique not as a weapon but as something closer to an answer.
Some would be against it, arguing that certain lines shouldn't be crossed.
Rei was not one of those people.
Yaga's fate in his father's books was death — killed by order of the higher-ups. Rei's stomach turned for a moment.
That death was no longer just part of a text. It was something that could happen sooner or later, in this world that was now his world, and honestly Rei refused to simply stand by and watch.
Yaga Masamichi. Kento Nanami. Choso. All victims of circumstance, all people Rei wanted to save if he could. He didn't know how yet.
He didn't know if he could. But the intention was there, settled somewhere quiet inside him, without drama or urgency — just the silent certainty of someone who had already made a decision without announcing it to anyone.
Rei's train of thought was interrupted by Yaga's deep voice.
"Kagami Rei." The principal looked at him from across the desk with the specific calm of someone who has seen too many things to be caught off guard by anything. "I'll get straight to the point. Why do you want to be a sorcerer?"
Rei had been expecting an attack — something like what had happened with Itadori according to the books. But nothing happened. Just the question, direct and unadorned, floating in the silence of the office.
Why do I want to be a sorcerer?
He repeated it to himself mentally, looking for the honest answer rather than the convenient one. That question had been circling his mind since he started reading his father's writings — what he would do if that world ended up becoming his reality. Now it was, and the answer was still the same it had always been, even if he took a while to find the words.
"Maybe..." Rei's gaze drifted around the room for a moment, until it landed directly on the eyes behind the principal's glasses.
Yaga saw eyes a teenager shouldn't have.
"I'm just looking for somewhere to belong." Rei wouldn't lie. His world had always revolved around his father, and that world had ceased to exist.
"When I started seeing curses I thought I was going crazy — no one else could see them." He scratched his cheek, that tic that appeared when he felt uncomfortable. "I was already strange. That made me even stranger."
A pause.
"But when I found out it was all real, I stopped feeling so strange." Rei said it slowly, like someone articulating something they had always known but never said out loud. "It was more like I had found the place I had always been looking for."
They say a sorcerer always has to be a little crazy. That was probably the case with Rei. The Jujutsu world was cruel, bloody, unpredictable — but at the end of the day the real world was too, and at least this one had rules that could be learned, enemies that could be seen, and people worth protecting. To Rei, the Jujutsu world felt even warmer than the world he had grown up in.
That probably said more about his childhood than about his sanity.
The first day at Jujutsu High was quiet. Gojo mentioned he had to leave for a mission, so Megumi spent the rest of the day showing Rei around the school — the buildings, the training grounds, the library, the infirmary. He did it with the same quiet efficiency he brought to everything, without unnecessary comments, pointing out what needed pointing out and moving on.
Rei was more grateful for that than he could have expressed.
He spent the rest of the day in the library, comparing what he found about Jujutsu with what he had learned from his father's books. There were similarities and differences — some things were described in more detail in the academic texts, others with more precision in Souta's writings. Rei took mental notes of both.
Since he had started discovering that everything was real, he had set concrete goals for himself. Among them were developing his cursed technique, refining the domain, and the reverse cursed technique. About this last one he had a basic notion — the concept of multiplying negative cursed energy against itself to generate positive energy — but if it were that simple, any sorcerer with enough energy could manage it. Clearly there was something more.
The following morning, before classes, Gojo found him in the dormitories and handed him his uniform.
"Is it customized for each student?" asked Rei, noticing that while very similar to the standard one, his had differences — the trousers somewhat looser, the sleeves cut at elbow length.
Gojo confirmed it with a smile that suggested he had taken more liberties than were strictly necessary. "I thought it would suit you better this way."
Rei looked at him for a second. He decided it wasn't worth questioning.
Along with the uniform came his student ID. Despite his abnormal amount of cursed energy, until he reached his true potential Rei was temporarily classified as a second-grade sorcerer. The feat of clearing the hospital alone backed him up — the curses weren't particularly strong, but the ease with which he had handled them was enough to justify the classification.
With Gojo busy with missions and classes yet to begin, Rei gave himself the freedom to use that time on what seemed most urgent: control of his cursed energy.
The problem was obvious from the start. Gojo had mentioned it the night at the hospital — he was constantly producing energy, releasing it without control like a tap someone had left running and never thought to close. That made him completely perceptible to any sorcerer or curse capable of sensing energy, which in terms of stealth was basically a disaster.
The first thing he tried was simply feeling it.
He sat cross-legged in the middle of the courtyard, closed his eyes, and paid attention to what he normally ignored. The energy was there — it had always been there, since before he knew it had a name. It flowed from somewhere inside outward without him asking it to, moving in all directions at once, dense and constant like the hum of something that never turns off.
Understanding it wasn't as difficult as he expected. Thanks to his father's books and some texts from the library, he already had a conceptual framework for what he was doing — and the Paradox, somehow, made the energy respond to his understanding faster than it should have. As though the innate technique and control were part of the same process.
Bringing it inward rather than letting it escape was the first step. It wasn't about suppressing it — that would have been pointless given the quantity he produced — but about redirecting it. Giving it a destination instead of letting it scatter. In the first attempts the energy simply ignored his instructions. In the following ones it started to respond, slow and clumsy like water learning to follow a new channel.
By the third day he could keep most of his energy contained for short periods. By the fifth he could do it in a relatively sustained way without losing concentration. It wasn't perfect — more was still leaking than he wanted — but it was real, measurable progress, which was exactly the kind of progress Rei knew how to appreciate.
Next came body reinforcement. With his amount of energy, Rei could saturate his body in a way few sorcerers could afford — and he discovered something interesting in the process: his production rate was high enough to regenerate energy faster than he spent it on basic reinforcement. In practice that meant he could keep his body reinforced almost indefinitely without emptying himself, which was a considerable advantage.
The technique itself — the Paradox — was something else entirely. Harder to train directly because its manifestations depended on understanding more than effort. Every time Rei managed to clearly articulate what he wanted the paradox to do, the technique responded. Every time he tried to force it without understanding the mechanism, nothing happened. It was less like training a muscle and more like learning a language — progress came from comprehension, not repetition.
That led him to spend more time thinking than moving, which would have seemed strange to any outside observer but made perfect sense within his own logic.
What he lacked most, he knew, was real experience. Missions. Combat against something that was genuinely trying to kill him. The days at the hospital had been useful but insufficient — grade-three curses were not exactly an exhaustive test.
Soon.
But first there was something he wanted to sort out. He had been at Jujutsu High for almost a week without visiting the infirmary — not because he hadn't had reason to, but simply because he hadn't found the moment. Today he did.
He knocked before entering, waited a moment.
"Come in," came from inside — a calm voice, without particular enthusiasm.
When he entered, the smell of medicine flooded Rei's nostrils. In some way it reminded him of visiting his father — that specific mix of antiseptic and something harder to name that existed in all the places where people go to be healed or put back together. It wasn't a bad memory. It was just a memory.
The infirmary was orderly and functional, with that look of a place that serves its purpose exactly without unnecessary ornamentation. Behind a desk at the far end was a young woman — or at least younger than Rei would have expected — with her hair pulled back and an expression that suggested she was used to people walking in with problems and preferred them to get to the point.
Rei took a moment before speaking.
"Good afternoon, Ieiri-san."
Ieiri Shoko looked up from what she was reading with the calm of someone who doesn't bother pretending anything surprises them. Her eyes registered him in under a second — new face, new uniform, no visible injuries. Their gazes crossed briefly.
"Kagami Rei, right?" she asked in that unhurried tone that gave the impression very few things in the world struck her as urgent.
Rei nodded, figuring Gojo had mentioned something to her already. Which was likely. Gojo mentioned everything, in the wrong order and with too much enthusiasm, but he mentioned it.
"You're not injured," Shoko observed, more as a statement than a question. She looked back at what she had in her hands, though without the same focus as before — the kind of divided attention of someone who listens even when they seem not to. "What do you need?"
Rei considered how to frame the request for a moment. It wasn't the kind of thing people asked every day.
"I wanted to ask a favor," he said finally. "I'd like to see how you use the reverse technique. Up close, if possible."
Shoko looked at him. This time with full attention, though her expression didn't change much — just a slight raise of one eyebrow that in her probably amounted to considerable surprise.
"To learn how to use it yourself."
It wasn't a question. Rei nodded anyway.
There was a pause. Shoko set what she had in her hands down on the desk with that specific movement of someone who has decided something without announcing it.
"It's not often someone comes and asks about that directly," she commented. It wasn't a compliment or a criticism — just an observation, delivered with the same neutrality with which she might note the weather. "I can explain how it works, if you want."
Rei thought about it for a moment. He knew from his father's books that Shoko was brilliant — the only sorcerer capable of using the reverse technique for healing with the level of precision her work required. He also knew she wasn't exactly known for her patience as a teacher. Not because she was unkind, but simply because it wasn't her calling — she preferred doing things to explaining them.
"I don't want to take up too much of your time," he said carefully. "Seeing it in action would be enough."
Shoko looked at him for one more second. Then she shrugged with the economy of movement of someone who has accepted stranger requests.
"Cut yourself."
Rei blinked. "Sorry?"
"Something small." Shoko gestured vaguely toward the edge of the desk. "There are scalpels in the left drawer. If you want to see the reverse technique in action you need a wound to heal."
Rei looked at the drawer. Looked at Shoko. Looked at the drawer again.
He opened it, took the scalpel with the same calm with which he might have picked up a pencil, and made a small cut on the back of his left hand. Clean, precise, without drama. Shoko watched him with an expression that could have been approval or simply indifference — with her it was hard to tell.
"Good." She moved closer, extending her fingers over the cut without touching it yet. "Pay attention to how the energy moves, not to the wound."
And then Rei felt something completely different from anything he had experienced until that moment.
The cursed energy he knew was dense, dark in a sense that had nothing to do with color — heavy, with that quality of something that comes from difficult places. The positive energy emanating from Shoko's hands was the opposite in almost every sense. Not warm exactly, but directional — it flowed inward rather than outward, it built rather than destroyed, it resolved rather than opened questions.
And yet it was the same energy. Transformed, multiplied against itself until its nature inverted, but recognizably the same at its origin.
The cut closed in seconds. It didn't scar — it simply ceased to be there, as though the skin had decided to remember its previous state and return to it.
Rei looked at the back of his hand for a long moment.
The energy doesn't disappear, he thought. It changes direction.
What the reverse technique required wasn't generating something new — it was taking what already existed and convincing it to move in the opposite direction while multiplying the very essence of the cursed energy against itself. And the Paradox, by definition, was precisely that — something that existed in two opposite states at the same time.
Rei extended his own hand. He closed his eyes for a moment. He felt the energy moving outward as it always did, and instead of redirecting it inward — which was what he had tried before without success — he simply created the paradox that the energy was moving outward and inward simultaneously. Two opposite states, coexisting. The Paradox doing what it always did.
Positive energy appeared between his fingers, faint and poorly controlled, but real.
Rei opened his eyes.
Shoko looked at him with the same expression as before — neutral, hard to read. But there was something different in her silence now. Sorcerers with a talent for the reverse technique weren't common — aside from Shoko herself, and Yuta, most sorcerers struggled to develop the reverse technique at all. Some never managed it.
"If you have any questions come see me. I have some books that might be useful to you," she said, as though the conversation had ended exactly where it was meant to end. Deep down, Shoko hoped Rei would eventually be able to heal others. That meant fewer bodies to deal with, fewer people she'd have to watch die.
Rei understood it was a farewell. He nodded, left the scalpel where he had found it, and walked out of the infirmary with the same calm with which he had entered.