Yami set down his fifth bowl of kaisendon with a satisfying clack against the wooden table. Not a single grain of rice remained. Not a single sliver of salmon. The bowl was so clean it looked like it had never been used.
Around him, the dining hall of the Zenin estate carried the low murmur of conversation. Servants moved between tables with practiced silence, their footsteps barely grazing the tatami. The room smelled of soy and vinegar and the faint bitterness of green tea left too long in its pot.
But nobody was talking about the food, every pair of eyes in the room had found its way to Yami.
A clan member three seats down leaned toward the man beside him, the sticky threads of the natto stretched between his chopsticks like cobwebs as he whispered, voice dripping with bitterness.
"Seriously. We sit here eating fermented rice and natto every single day. And this brat swallows expensive seafood like it is water, five bowls, that is more than some of us eat in a week."
The man beside him said nothing. He simply looked down at his own tray and chewed a little slower.
Yami did not acknowledge them, he had learned early that acknowledging complaints only invited more of them. Instead, he raised his hand toward a passing servant without looking up.
"Another one."
The servant hesitated for a fraction of a second before bowing and retreating toward the kitchen.
Bowl number six arrived moments later. A generous mound of glistening rice crowned with thick cuts of tuna, salmon, and yellowtail.
Yami picked up his chopsticks and then he stopped.
A particular itch along the back of his neck that told him someone was watching.
Yami lifted his head slowly and scanned the room.
He found the source almost immediately.
A small boy, probably around his own age, maybe a year younger. Green hair that fell in unruly waves around a round face. His features were soft in the way that children's features are before life has the chance to sharpen them but his eyes were something else entirely. They were wide and bright, almost glittering, like a kid watching fireworks for the first time.
The boy did t look away when Yami caught him staring. He did not flinch or pretend to be interested in something else. He just kept looking, that strange admiration burning openly on his face.
Yami stared back for a couple of seconds and the boy did not blink at all.
Yami turned back to his bowl and ate.
Then a presence settled beside him, the boy had planted himself right next to Yami on the bench, cross-legged, hands on his knees, back straight like he was attending a formal lesson.
Yami ate three more bites in complete silence before the absurdity of the situation finally outweighed his appetite. He set his chopsticks down across the rim of the bowl and turned his head just enough to look at the kid from the corner of his eye.
"Well," Yami said flatly. "Make yourself interesting."
The boy blinked and his head tilted to the side like a bird trying to make sense of its own reflection.
"You look ordinary," the boy said.
The words came out blunt, the honesty that only children and fools were capable of.
Yami raised an eyebrow but said nothing, the boy's eyes lit up again, that starry brightness returning in full force, and his voice dropped into a tone of open, unhidden reverence.
"Toji-san looks much better than you."
'Toji.'
Yami's eyes narrowed and his pupils contracted.
"Naoya?"
The boy's face split into a grin so wide it could have cracked his cheeks. He nodded rapidly, clearly pleased.
"I did not know Big Brother knew me!" Naoya chirped.
"He just lives in his own world, ignoring everybody. I thought maybe Big Brother did not know anyone's name at all."
Yami did not respond immediately.
Naoya Zenin.
The future head of the Zenin clan in another timeline. A prodigy in his own right. A man who would grow up to worship Toji Fushiguro with a fervor that bordered on obsession, and who would carry a worldview so twisted and rigid that it would eventually become his coffin.
But right now he was just a kid with green hair and stars in his eyes.
'He said I live in my own world. That I ignore everybody.' The thought turned over slowly in his mind, examined from every angle.
'That is not the kind of observation you make from a single encounter.'
'That means he has been watching me. For a long time.'
The realization settled in his chest and Yami asked.
"Have you been obserrrving me for a while?"
Naoya's grin faltered. The stars in his eyes dimmed just slightly, replaced by the unmistakable flicker of a child caught doing something he was not supposed to do.
"I... uhh." He rubbed the back of his head with one hand, fingers tangling in his green hair. His laughter came out thin and forced. "Well, you see..."
He trailed off and Yami did not press further, Naoya's reaction was answer enough.
But the confirmation brought no comfort. If anything, it made the cold stone in his chest sink deeper.
Yami clicked his tongue.
'A kid. A dumbass little kid was following me around, watching me, studying my habits and my patterns, and I did not notice.'
'Not once. Not a single time did I feel his presence.'
His jaw tightened as a thought settled in.
'And if a child can do it, what about someone who actually knows what they are doing?'
The implications unfolded in his mind like a series of dominos falling in sequence, each one worse than the last.
'Naobito would have people on me. That is a certainty.'
'And if I could not even detect a child...'
Yami's expression did not change on the outside. To anyone watching, he looked the same as always but inside, a gear had begun to turn.
'I cannot activate the Predator Eye all the time. It drains too much energy and draws too much attention. I need another method. Something passive. Something constant. Something that works even when I am eating or sleeping or doing nothing at all.'
His eyes drifted downward in ponder to Naoya's shadow.
The shadow of a small boy sitting cross-legged on a wooden bench.
But to Yami, in that moment, it was a revelation.
A smile crept across his face.
Naoya noticed the smile and leaned forward, curious. "Big Brother? What are you..."
"Thanks, Naoya. Bye."
Yami stood up from the bench, leaving his sixth bowl of kaisendon half-finished for the first time in his life.
Naoya sat alone on the bench, blinking at the empty space where Yami had been sitting. His mouth hung slightly open.
"...Huh?"
By the time the sound left his lips, Yami was already gone.
---
The training room was located in the eastern wing of the Zenin compound, separated from the main living quarters by a long corridor lined with wooden pillars but Yami had not come here to fight.
Yami moved through the room, quickly closing the three doors: two sliding doors and a heavy wooden one to the storage closet, next, he turned off the lights.
Total darkness.
Had someone walked in at that moment, they might have thought Yami had lost his mind. A five-year-old boy standing alone in a pitch-black room with every exit sealed shut. It looked like the setup to a horror story, or a breakdown.
But that was not the case.
Yami stood at the center of the room with his eyes closed.
"Ten Shadows," he murmured into the dark. "The inherited technique of the Zenin clan. A method of summoning and subjugating shikigami using shadows as a medium."
He paused for a brief moment and then continued.
"But that is just one interpretation."
"The prevailing understanding treats shadows as a medium,"
"But what if that is not all it is? What if the shadow is not just a container but a conductor? Not just a medium of summoning, but a medium of motion? Of connection? If shadows are linked to me, and every person casts a shadow, and every shadow touches the ground the same way mine does..."
"Then I should be able to feel them."
As he tried to actualize it, nothing happened, yami did not move and he simply waited.
After five minutes of training Still nothing.
But Yami was not discouraged he continued thinking, the theory was sound, but theory without application was just philosophy. He needed to bridge the gap between concept and reality.
'What if I use cursed energy?'
Cursed energy flowed Into his shadow.
At that moment, Yami felt it, a meek pulse.
"There," he whispered
Yami opened his eyes and the darkness stared back.
"I can only sense my own shadow."
He had hoped that feeling his own shadow would be the first domino. That the connection would ripple outward, spreading from his shadow to the shadows around him, linking him to every dark shape in the room like a spider sitting at the center of its web.
But that was not what happened. His awareness ended at the borders of his own shadow. Beyond that, nothing. The shadows of the walls, the floor, the ceiling, the training dummies stacked in the corner... all of them remained invisible to this new sense.
'I need more practice.'
His expression was grave, he looked around the dark room, though there was nothing to see. Then he moved to the far wall by memory alone, his feet silent on the wooden floor, and retrieved something from the rack of training equipment.
A simple wooden bokken, a training sword.
'Perfect.'
Yami returned to the center of the room and placed the bokken on the floor in front of him. Then he stepped back three paces and closed his eyes again.
He let his cursed energy flow downward once more.
Now he reached outward, extended his awareness beyond the borders of his own shadow, stretching toward the spot on the floor where the bokken lay.
Nothinghappened, he pushed harder tried to force the connection into existence through sheer will.
Nothing again
He shifted his approach. Instead of pushing outward, he tried pulling. Drawing the bokken's shadow toward his own, like a fisherman reeling in a line.
He tried flooding the floor with cursed energy, saturating the entire surface in hopes that the bokken's shadow would light up like a marker in a sea of ink.
Yami lost count of how many times he tried.
And then, somewhere between the fifteenth and twentieth failure, the answer arrived, as a slow, realization.
He opened his eyes."I know my own shadow deeply," he said aloud. The habit of narrating his thoughts was something he had picked up recently.
"It is mine. It is an extension of my body, my cursed energy, my identity. Of course I can sense it. I am it."
He looked down at the bokken.
"But this stick is not me. Its shadow is not mine. It is a foreign entity. And the Ten Shadows technique was never designed to sense foreign shadows. It was designed to summon shikigami through my own shadow. Everything about the technique points inward, not outward."
"So if I want to sense another shadow, I cannot rely on the technique alone. The technique gives me the mechanism, the ability to interact with shadows at a fundamental level. But the targeting, the identification, that has to come from me."
He knelt beside the bokken and picked it up
"I need to know this object. Not in the way I know my own shadow, instinctively and completely, but in a structural way. I need to understand what it is made of. How it is built. What defines its physical existence in space."
He set the bokken down again and pondered.
"I need to visualize its structure."
The realization branched outward in his mind, connecting to other things he already understood. This was different from the identity framework required by Merged Soul Mode. In that state, recognition was philosophical. You needed to grasp the essence of something, its meaning, its place in the world, the idea of it.
Shadow Sense, as he was beginning to call it, operated on the same foundational principle of recognition but the thought process was entirely different. Where Merged Soul Mode asked "What is this thing?" in the philosophical sense, Shadow Sense asked "What is this thing made of?" in the physical sense.
Two interpretations of the same underlying truth, branching in opposite directions like a river splitting around a stone.
Yami closed his eyes one final time and focused on the bokken.
He built the image in his mind piece by piece, then he opened his eyes and walked to the wall.
He needed light for this next part.
Including the bokken's shadow. A thin, dark line extending from the base of the training sword toward the far wall.
Yami returned to his position with his eyes closed, he felt his own shadow.
Then he reached outward, holding the visualization of the bokken's structure firmly in his mind and he felt it but it was there.
Yami exhaled.
'It worked, barely, imperfectly, unreliably but it worked.'
And in the same breath that relief arrived, so did the full scope of the problem.
Yami opened his eyes and stared at the flickering lamp light across the walls.
"To sense a person," he said slowly, "I would need to know the structure of that person. Their body. Their composition. The specific arrangement of bone and muscle and tissue that makes them who they are physically."
"And every person is different. Every body is unique. Height, weight, bone density, muscle distribution, organ placement... it varies. It always varies. I could not use a single template and apply it universally. Each person would require their own visualization."
The scale of the problem was staggering. To use Shadow Sense on a single person, he would need to construct a detailed physical model of their body in his mind and to use it on multiple people simultaneously, he would need to hold multiple models at once.
For a grown man with decades of experience and a mind trained for multitasking, it would be difficult.
For a five-year-old, it was borderline impossible.
"I need to make this automatic," Yami muttered. "I need to build a baseline. Common traits. Things that all human bodies share regardless of individual differences. If I can create a general framework and let the technique fill in the specifics on its own..."
The solution existed. He could see it, distantly, like a mountain visible through fog. But the path to reach it was long and steep and lined with a thousand small failures.
A faint smile touched his lips. Despite the frustration, despite the limitations, despite the sheer absurd difficulty of what he was attempting, there was something in the struggle that called to him.
He could not help but form the words in his mind.
'The beauty of jujutsu. The joy that cuts like guilt and yet endures like stone.'
'That is a good line. I should remember that one.'
And then his head exploded, not literally but it might as well have been.
His vision whited out and his legs buckled.
His hands flew to his head, fingers digging into his scalp, pressing against his skull.
"AHHHHH!"
This was the price.
The brain of a five-year-old was not built for this. It was not meant to process the kind of multi-layered, simultaneous calculations that Shadow Sense demanded.
An adult sorcerer might have managed it.
But Yami was not an adult.
He had pushed that hardware past its breaking point.
And the price was paid.