Kenji had bought a goldfish from the market that morning for the lesson. It was fat, orange and white, about ten centimeters long, and currently drifting around a glass bowl on the workshop table.
Daiki stared at the goldfish swimming in the bowl on the table.
"Tell me how the technique works," Kenji said from beside him.
Daiki took a breath. He had been studying the theory for a while, and his father had gone over the details so many times that the explanation felt burned into his head. Still, understanding the steps wasn't the same as putting his mind into another living body.
"I send my consciousness toward the target in a straight line. And once it connects, I enter the target and control its movements. My own body goes unconscious while I'm inside, so I can't defend myself. If the target gets hurt, I feel it too. To return, I form the release seal mentally and pull my consciousness back into my body."
"What if you miss?"
"Then my consciousness keeps going until it hits something or breaks apart on its own. My body stays unconscious until I return, which means I'm helpless the whole time."
"Range?"
"About five meters at my level. Past that, the connection starts to fall apart."
"And the worst thing that can happen?"
"Someone reaches my body while I'm out. They could do anything they wanted."
"That's why we're doing it here first." Kenji gestured around the workshop. "I'll be standing next to you the whole time. Your body is safe. Don't think about anything except reaching the fish."
Daiki nodded.
"But why a fish?"
"Its mind doesn't have much complexity, so there won't be much resistance when you enter. Your consciousness should slide in before the fish even understands something is wrong. If you make a mistake, the worst thing that happens is the fish jumps out of the bowl. This is only your starting point. Once you can enter and leave a simple target without trouble, we'll move on to something more complex."
"Got it."
"There's one thing you need to remember before you try. When the technique connects, you'll feel the fish's senses. It won't be comfortable. Your instinct may be to panic and rip yourself out of the connection, but don't do that. Stay calm, get your bearings, and release the technique properly. If you force your way out while your mind is still tangled with the target's, the feedback can leave you with a headache for days."
He nodded toward the bowl.
"Whenever you're ready."
Daiki formed the hand seal and focused on the goldfish.
The Mind Body Switch Technique connected, and his awareness narrowed into a thin line.
For an instant, it felt like he had plunged headfirst into freezing water, only the shock wasn't against his skin. It passed through his mind. His consciousness crossed the three meters between him and the bowl, and sank into the fish before he could register the movement.
The goldfish's mind was barely there. There were instincts, but nothing that pushed back against him. His consciousness slipped into place awkwardly, like his hand had gone into a glove made for the wrong shape.
Then the fish's senses reached him.
Colors spread wider than they should have, bending through the curve of the glass. Sound arrived as faint vibration through the water. His new body responded through fins and a tail, and even the smallest impulse sent him drifting the wrong way.
Panic rose before he could steady himself.
Stay calm.
He pictured the release seal the way his father had taught him, then pushed chakra through it.
The connection broke.
He came back with a gasp, shoulders jerking as the workshop snapped into place around him. The table was under his hands again, and his feet were on the floor. A dull ache pressed behind his eyes, but it wasn't unbearable.
"How long was I inside the fish?"
Kenji laughed as soon as he heard the question, but he caught himself quickly and looked at the clock.
"Four seconds."
Daiki stared at him. "Why did you laugh? Was I bad?"
"No," Kenji said, smoothing his expression back into place. "I just thought of something. Anyway, for a first attempt, that was excellent. Most Yamanaka need three tries before they enter the target at all. You connected on your first try."
Daiki hadn't thought about that. He had been too busy trying not to panic inside a fish.
"Is the fish okay?"
They both looked down at the bowl. The goldfish was swimming in tight circles near the bottom.
"It's confused, but it's fine."
Daiki kept watching the fish for another few seconds. "Can I try again?"
Kenji shook his head. "Give it a little time. Your chakra's still stirred up."
Daiki didn't like waiting, but he did as he was told.
On the second attempt, he lasted eleven seconds. The fish's senses still felt wrong, but they didn't crash over him as hard. He could tell which reactions belonged to the fish and which thoughts were his own, even when both tried to pull him in different directions.
On the third attempt, he lasted twenty-three seconds and managed to guide the fish through a slow circle.
"Fourth attempt," Daiki said as he formed the seal again.
This time, he stayed connected for a full minute. He tested the fish's movement, learned how much force sent it darting forward, and how little it took to keep it hovering in place with its fins. By the time he released the technique, the headache had almost disappeared.
"That's enough for today."
"Come on, one more..."
"We'll continue tomorrow."
Daiki looked like he wanted to argue, but Kenji's tone made the answer clear.
---
Daiki trained with the Mind Body Switch every day for the next three weeks.
Kenji had expected him to improve, but not as quickly as he did. By the end of the first week, Daiki could enter the goldfish and pull himself back out in less than a second. Once that became reliable, Kenji stopped letting him repeat the easy part and had Honoka borrow a cat from one of the neighbors.
The cat was a bad-tempered tabby that made its opinion of the training clear from the start.
Unlike the goldfish, it didn't go still when Daiki pushed his mind into it. There was something in the way. Daiki had to press through that resistance before he could take control, and the first few tries ended with him clutching his head while the cat glared at everyone in the room.
Still, he kept improving.
Cats had dislikes, habits, and a clear sense that their bodies belonged to them. Taking control meant forcing that sense of self down for a short time, and that demanded more spiritual energy than the goldfish ever had. It also punished sloppy focus much faster.
Daiki adjusted to it faster than Kenji expected.
By the end of the second week, he could hold the cat for short stretches. By the third, the headaches were lighter, the failures were fewer, and even the cat seemed less offended afterward.
---
At the Academy, the students had begun moving toward their clan specializations, and the gap between them was starting to show.
Sasuke made that clear during one of Mikoto's practical lessons.
The class had already moved past simple stances and sparring drills. These days, her lessons often shifted into broader combat training, especially when students were ready to show what their families had been teaching them outside the Academy.
When she asked for volunteers to demonstrate a newly learned technique, Sasuke stepped forward.
No one looked surprised.
He raised his hands and formed the seals. Then he drew in a deep breath, gathered his chakra, and exhaled.
A massive fireball erupted from his mouth and tore across the training field.
The students closest to the front recoiled as the heat rolled over them. The fire carried forward for nearly thirty meters before it broke apart, leaving the air shimmering and the ground lightly scorched.
"Excellent form. Take your place."
Sasuke returned to the line.
Naruto, standing beside Daiki in the second row, stared at the fading scorch marks.
"That was insane!"
"Yeah..."
Naruto's expression shifted from awe to frustration. "Sasuke's got fire techniques. You've got puppets and Yamanaka stuff. Karin's got sensor abilities. Hinata's got the Byakugan. Even Kiba's got Akamaru. So what's mine? I need to get better..."
Daiki looked at him and couldn't give an easy answer.
Naruto's strength was obvious if you knew what to look for. His chakra reserves were ridiculous, far beyond what someone his age should have, but he still didn't have a proper outlet for them. It was like trying to push a lake through a narrow pipe. The power was there, but the method wasn't.
---
The suggestion came from someone Kushina hadn't expected.
Kenji rarely spent time at the Academy, but he still came to parent observation days when Honoka insisted. He said it gave him a useful look at how the next generation was developing, and Kushina suspected that wasn't just an excuse.
That day, the class was practicing tree climbing on the training field behind the Academy. It was a standard chakra control exercise, simple in theory and miserable for anyone whose control wasn't steady.
Most of the students had already figured it out. Daiki walked a few steps up the trunk and kicked off. Karin slipped on her first attempt, adjusted, and made it halfway up the next time. Sasuke had gone several meters above the ground and was standing on the bark with his hands in his pockets.
Naruto fell again.
He groaned and pushed himself up before Iruka could even reach him. Then he ran at the tree again. For a second, his foot held. Then his chakra surged, the bark cracked under the pressure, and he was thrown backward onto the grass.
The other students had watched him fail too many times for it to be interesting. Iruka moved closer and began explaining again.
Kushina stood at the edge of the field with her arms folded.
"His control hasn't improved."
Kenji followed her gaze.
"The problem probably isn't effort."
"I know."
"It isn't talent either." Kenji watched Naruto adjust his stance for another try. "His chakra isn't moving cleanly. The Nine-Tails' chakra is always there in the background, and even with Minato's seal, it's still interference. Anything that needs a steady, precise flow is going to fight him the whole way."
Kushina didn't argue. She had known that better than anyone.
"So maybe the answer isn't better control. Maybe it's using a technique that doesn't punish him for having too much chakra."
Kushina glanced at him. "What are you thinking?"
"Has he tried the Shadow Clone Technique? His reserves can handle it."
Naruto charged the tree again. His foot stuck for a second before the bark cracked under the pressure and threw him backward. He hit the ground on his back and stared up at the sky.
Kushina watched him for several seconds. "You think it would work?"
"It's worth testing. If it works, it gives him more than a technique."
Kushina's expression shifted as she understood where he was going with it.
Naruto got back to his feet, covered in dirt and still glaring at the tree.
"I'll talk to Minato tonight."
---
The puppet Kenji built for Daiki's ninth birthday was nothing like the training model.
It stood about sixty centimeters tall, with a light frame Daiki could guide using chakra strings, but that was where the similarities ended. The old training puppet had been stiff and simple. This one moved with a cleaner snap in its joints. The torso had been reinforced too, so it wouldn't break the first time Daiki slammed it into a wall by accident.
Daiki was still staring when Kenji placed it on the workshop table.
"This is your combat training puppet."
Daiki's eyes dropped to the forearms. "Combat?"
Kenji pressed one finger against a hidden catch. A short blade slid out from the puppet's arm. It was only about fifteen centimeters long, but to Daiki, it might as well have been a sword.
"The blades are dull," he said before his son could get too excited. "They won't cut anything worse than cloth."
Daiki touched the puppet's arm and found the thin seam around the blade housing.
"This is incredible!"
"If you train every day, the joints will probably need replacing in six months. The springs are adjusted for your current chakra output, so I'll have to recalibrate them as you get stronger. The blades are temporary too. Once you can use them safely, we'll discuss sharper ones."
Daiki picked up the puppet with a grin and connected two chakra strings to it. His fingers shifted, and the puppet walked across the table. Its steps were much smoother than before, with less dragging at the knees and less wobble in the torso.
He added two more strings, linking them to the arms while the first two stayed on the legs. The puppet walked, raised one hand, waved, then turned in place.
The blade mechanism threw off his control. When he tried to extend one blade, the puppet's right leg dragged across the table. After he fixed the leg, the arm started moving late, and when he focused on the arm, the body tilted forward.
He kept trying, with his father standing nearby to guide him when needed. Sometimes Kenji pointed out the mistake. Sometimes he took the strings, demonstrated the movement once, and gave them back without saying more than he had to.
After nearly two hours, Daiki managed to make the puppet step forward and extend one blade at the same time.
Kenji's eyes narrowed slightly. "You're leading with the left arm to cover the delay on the right."
Daiki looked down at the puppet. "It worked, didn't it?"
"If you keep doing it, it'll become a pattern. Anyone who watches you for thirty seconds will know what comes next."
"So what do I do?"
"Fix the delay. Don't build a habit around it."
Daiki frowned and adjusted the chakra flow in his right hand. The puppet reset, took another step, and extended its right blade again.
This time, the arm was closer.
Kenji nodded. "That's the principle."
---
It happened on a Wednesday.
Daiki was in the workshop, practicing solo. His father was at the Hokage's office. His mother was out running errands. He had the space to himself, which meant he had the freedom to experiment without his father's watchful eye catching every mistake before he made it.
The combat puppet sat on the table, connected by four chakra strings. He'd been running through movement drills when a thought occurred to him.
He'd been practicing Mind Body Switch for weeks. And there, sitting in front of him, was a puppet.
It had a framework designed to receive and respond to his mental commands. It was, in a sense, already an extension of his body.
What if Mind Body Switch could work on it?
The logical part of his brain said this was probably a bad idea to try alone.
But the nine-year-old part of his brain said: yeah, but what if it works?
In the end, he chose a compromise. He kept his chakra strings attached as a safety measure. If the technique failed, the strings would provide a path for his consciousness to return to his body. At least, that was the theory.
"Mind Body Switch Technique!"
The sensation was different from entering the fish or the cat. There was no biological awareness waiting to receive him. His consciousness struck the puppet's frame and began to spread.
It flowed like water across a flat surface, following the chakra pathways he had constructed through months of practice. His awareness moved along the connections, traveling from the puppet's right arm to its left, down through its legs, and up into its torso.
There was no resistance.
He flexed the puppet's right arm. It responded instantly. There was no delay, unlike chakra strings that required his commands to travel and translate into movement.
He moved the puppet across the table. When it reached the far side, he shifted his focus to the right forearm and pushed a command through the chakra string.
The hidden blade slid out.
He retracted it, extended it again, and tried to smooth out the timing, but the second attempt already felt heavier than the first. A sharp pressure gathered behind his eyes, and his spiritual energy began to drain faster than he could steady it.
He quickly cut the technique off, and his awareness snapped back into his body so abruptly that he nearly fell from his chair.
"Ow."
Pain throbbed through his head. His hands trembled uncontrollably, and his chakra reserves felt dangerously thin, yet he was smiling.
He remained seated for the next ten minutes, waiting for the headache to fade as he replayed the experience in his mind.