The quirk registration office was a government building two subway stops from the orphanage, beige and functional, with a waiting area that smelled like institutional carpet and a front desk staffed by a woman who had processed enough quirk registrations that the wonder had fully left the procedure and what remained was clean, efficient bureaucracy.
I went on a Saturday in April, thirteen years and one month old, accompanied by the orphanage's administrative coordinator, a man named Sugimura who handled the official business of the children in his care with the quiet competence of someone who had done it many times and found it neither interesting nor unpleasant. He brought a folder. He sat in the waiting area and read something on his phone while I was called to a small room with a nurse and a technician who explained the registration process in the tone of someone who gave this explanation several times per day.
The process involved a physical assessment and a demonstration. I demonstrated. The nurse noted enhanced grip strength and skeletal density above average for my age group. The technician ran a standard quirk-factor analysis and found what he expected to find, because I had reinforced my body to the level of someone with a straightforward physical enhancement quirk and held it there steadily for the entire assessment.
"Super Strength and Enhanced Endurance," the technician said, typing. "That's the working classification. Does that feel accurate to you?"
"Yes," I said.
He typed. The nurse made a note. The woman at the front desk processed the paperwork and produced a card with my name and my registered quirk type and handed it to Sugimura, who put it in the folder and took me to a noodle place nearby for lunch because that was apparently the tradition he had established with the orphanage children on registration day, and I ate my noodles and answered his mild questions about school and thought about the fact that the official record of me was now a clean and useful lie.
Good. That was exactly what I needed it to be.
The serious planning began that spring.
Not the vigilante work itself, that was still a year away minimum, I had set myself a hard floor of fourteen before operating with any regularity and I intended to hold it. But the architecture. The identity. The practical construction of Sukuna as a presence in this world.
The appearance question I had already resolved in broad strokes. The transformation, the Sukuna look, grey skin and the markings and the four arms, was going to be the product of cursed energy shaped around my body rather than any permanent alteration. I understood the mechanism in the same way I understood all of Sukuna's techniques, through years of attentive watching and reading and the intuitive grasp of the underlying logic that came from carrying the same energy in my own body. I had not tried it yet. I was building toward it.
The practical questions were more immediately pressing.
Clothing. Whatever I wore operating as Sukuna needed to be dark, nondescript, and not traceable to Ryo Shiba, which meant not purchased anywhere near the orphanage or anywhere I was regularly seen, and paid for in cash. Not immediately available to me in useful quantities but solvable with time and planning.
Movement. I needed to know the city at night well enough to move through it without using major streets, to have multiple routes in and out of any location, to know which areas had camera coverage and which did not. This was legwork, straightforward and accumulative. I had been building this knowledge from the roof and would continue building it through careful, incremental expansion of my operational range.
Evidence. The first man in the alley, the elastic-armed one, was still in the court system. I had been watching that case in the news with moderate attention. Nothing had connected the incident to any other person. The cut in the second man was unexplained and had been attributed in the police report to an unknown sharp instrument, which was technically accurate in the least useful way possible.
I needed to stay unexplained. Not unnoticed, which was probably not achievable once I started operating with any consistency, but unexplained. Sukuna would be seen. Sukuna would accumulate a presence in this world. What Sukuna could not be was traceable to Ryo Shiba, orphan, student, registered Super Strength quirk user, current resident of a state care facility in this ward.
The transformation was the key to that and I needed to get it functional.
I tried it for the first time on a warm night in May, alone on the roof at two in the morning with the city spread out on all sides and nobody looking at me.
I had been approaching it the way I approached all the techniques, conceptually first, building the internal map before trying to execute, understanding what I was asking the energy to do so that when I asked it I was asking clearly. What I was asking was for the energy to shape around me rather than into me, to act as a second surface rather than a reinforcement of the existing one, and to take the form I had carried in my memory since before I could walk.
The first attempt produced nothing visible and a significant energy expenditure.
I breathed through the expenditure and thought about what had happened.
The energy had gone out and found no clear instruction for the form. I knew what Sukuna looked like. I had seen Sukuna rendered in animation and in manga panels and in my own early childhood impressions of what I was carrying. But knowing what something looks like and giving energy a precise enough blueprint to construct it are different things, and I had given the energy a rough sketch when it needed a technical drawing.
I spent two weeks doing nothing but building the internal image. Not practicing the technique. Just sitting, eyes closed, and constructing Sukuna's appearance in my mind with the same patient precision I had used to map my energy reserves years before. Every line of the facial markings, the exact quality of the skin tone, the proportions of the additional arms, the specific way the eyes looked when all four were present. I built it until I could hold it in my mind without any element becoming vague.
Then I tried again.
The energy went out and found a clear instruction and followed it and I looked down at my hands and saw four of them.
I stood very still on the roof and breathed.
The additional arms had full sensation, which I had wondered about and was now not wondering about. They moved when I directed them, slowly at first, with the particular deliberateness of moving something you are not used to having but can feel completely. The grey skin covered everything visible. I could not see my own face but I raised one hand to it and felt the raised lines of the markings along the jaw.
I held the transformation for forty-three seconds before the energy expenditure became significant enough that I let it dissolve.
I sat down on the roof and put my actual two hands on my actual knees and stared at the city.
"Okay," I said quietly.
Then, because it had worked and because I was alone and because thirteen years of building toward something deserved one honest moment of acknowledgment before I moved back to the work, I laughed. Brief, quiet, the sound disappearing into the city noise around it.
Then I got up and began the reliability training.
Summer at thirteen was the best summer of my life in this body, which is a sentence that requires context to not sound pathetic.
I had the transformation at thirty seconds reliable by June, two minutes by August, with the energy expenditure decreasing as the technique became habitual in the way all techniques did. I was running Cleave at ninety percent. Dismantle was completely automatic, the technique available on demand the way a physical reflex is available, without conscious initiation required.
I had started working on something I had no name for yet, which was the application of Reverse Cursed Technique at its most basic level. The self-healing capability. In JJK terms, RCT worked by multiplying negative energy by negative energy to produce positive output, healing rather than harm. I understood the theory with the clarity of someone who had seen it explained multiple times. I could not yet produce the multiplication. I could produce the negative energy in controlled quantities. The multiplication step was where I was stuck.
This did not frustrate me the way it might have frustrated someone with less patience. It was genuinely difficult. It was supposed to be difficult. Gojo had described it as something that even skilled sorcerers failed to master, and I was a thirteen-year-old orphan working alone without instruction in a world that had never heard of the technique I was trying to recreate. The pace was appropriate to the conditions.
I kept working on it and kept working on everything else simultaneously and the summer moved around me hot and slow and full of productive hours.
September brought a new school year and a development I had not specifically anticipated, which was that I was placed in an advanced academic track for my age group, which meant a smaller class, higher expectations, and significantly more interesting coursework.
It also meant new classmates, which required a brief recalibration of the social environment.
There was a girl named Hana who sat two seats to my left and who had a quirk that allowed her to read emotional states as colors, which she had apparently mentioned to the class the previous year and which had resulted in a social dynamic that was faintly exhausting for her because people were always asking her what color she was seeing. She handled it with a dry patience I recognized and respected.
She turned to me on the second day and said, without preamble, "You're a very unusual color."
"Is that good or bad," I said.
"I'm not sure yet," she said. "Most people are pretty predictable. You're something I haven't seen before."
I looked at her for a moment. She was not asking anything I needed to answer carefully. She was making an observation with the direct manner of someone who spent a lot of time reading things accurately and had learned to trust her own data.
"I'll take unusual," I said.
She made a small sound that was not quite a laugh and turned back to her notes.
That was the entirety of our first conversation. Over the following weeks it extended into something that was not quite friendship but was a comfortable and occasionally interesting adjacency. She did not ask about the color again and I did not ask what it was. That felt like a reasonable arrangement and we both appeared to find it satisfactory.
October. Thirteen and a half.
I lay on the roof on a clear night and looked at the stars, which were not very visible from the city but whose presence I could infer from the few that made it through the light pollution, and I ran a full inventory.
Dismantle: complete. Cleave: functional and reliable. Transformation: stable up to two minutes and improving. RCT: in progress. Body reinforcement: strong enough to take hits from most opponents my age and above with minimal damage. Range on Dismantle and Cleave: twelve feet and extending.
Power level, honest assessment: genuinely dangerous to unprepared opponents. Not yet sufficient for the higher-level threats I knew were coming years down the line. Adequate for the vigilante work I intended to begin in six months or so.
Timeline: approximately two and a half years until UA. Everything was moving at the pace it needed to move at.
I was not satisfied, because satisfaction was a state I did not permit myself to settle into for long. Satisfaction was the thing that made you stop checking the work. But I was not unsatisfied either. I was, accurately, on track.
The city breathed around me, dark and wide and full of things happening in it that I could not see from here but knew the shape of. Somewhere out there the League of Villains was in its early formation. Somewhere All For One was operating through proxies and consolidating power with the patience of someone who had been doing it for generations. Somewhere Izuku Midoriya was thirteen years old and quirkless and running anyway.
Somewhere in this city, probably more than once tonight, someone was in an alley with a knife and someone else was at the wrong end of it.
I was not ready yet.
Six months.
I pressed my hand flat against my sternum and felt the fire, which was not small anymore, which was something substantial and real and growing steadily toward what it was always going to become, and I made the same promise to it that I made to myself.
Six months. Then we begin.