"Take this, you jerk, Sasuke!"
"Damn it, you dead-last! Take this!"
They splashed water back and forth, locked in a fierce battle.
As they fought, the two suddenly realized something was off. They both noticed Hui forming Hand Seals to perform a technique.
"Whoa! That's amazing! Is this what ninjutsu looks like? Hey, Hui, could you teach me?"
As a model student, Sasuke could tell from Hui's Hand Seals that it was only a basic ninjutsu.
"Hmph. It's just a basic Water Release Ninjutsu, and you're this excited? A dead-last is still a dead-last."
Sasuke suddenly realized something was off. Water Release? Was there anyone in the Uchiha Clan who knew Water Release? His big sister Chiyuki was one. Other than her, there didn't seem to be anyone else.
The ninja watching nearby had already assumed combat stances. In battle, trusting an opponent's Hand Seals and misjudging the power of their ninjutsu was a grave mistake.
Hui hadn't noticed anything. His attention was fixed on the Water Ball in his hands.
At first, he'd only been curious to see how big a Water Ball he could make. But as it grew bigger and bigger, he started to notice a problem. He was by the river, sure, but—
Was there really this much moisture in the air? Or had it all been converted from his chakra?
That didn't make sense. From a quantitative standpoint, it was impossible to explain. The Water Ball in front of him was clearly bigger than he was. Its mass was obviously greater than his own. Besides, his father had already demonstrated that chakra was matter.
The sight left Hui bewildered. He couldn't make heads or tails of it.
He released the Water Ball, and it fell onto the sand and stones beside the river before flowing into the river.
Hui looked at the soaked sand and stones and furrowed his brow again.
Just then, Sasuke and Naruto came over from the river.
Naruto was about to speak, but Sasuke covered his mouth and gestured for him to be quiet.
Naruto saw the gesture and fell silent.
When a ninjutsu technique wasn't released from a ninja's hands, its traces would soon vanish from the world once its chakra dispersed.
But when a technique like this Water Ball came into contact with a large amount of physical matter, its chakra behaved exactly like matter in this world: it soaked things and flowed just the same. It was indistinguishable from real water.
From the standpoint of matter, Hui could understand. Chakra from ninjutsu displayed the same properties as matter.
What he couldn't understand was the mass. If he remembered correctly, his father had once told him that mass-energy was always conserved. Matter couldn't be created from nothing or vanish into nothing. Yet everything before him challenged that law.
Practice was the sole criterion for testing truth. Did that mean what his father had told him was wrong?
Hui figured that even if his perception was off, he couldn't possibly confuse having something with having nothing.
He picked up two stones of roughly the same size. One had been soaked by the water from his ninjutsu; the other had been soaked by ordinary water.
Hui tried to understand the problem through a comparative experiment.
Minute by minute, time passed. Under the blazing sun, Hui saw the result he'd been looking for. The water from the ninjutsu evaporated faster. Maybe it hadn't evaporated at all—it had simply vanished completely.
This phenomenon made him question the conservation of mass-energy once more.
Hui was staring intently at the stones when a shadow suddenly fell over them. He looked up sharply and saw concern in Naruto's eyes.
Seeing that Hui had finally snapped out of it, Naruto said, "Hui, are you really okay? You've been staring at these dumb rocks forever."
Sasuke didn't say anything, but he clearly felt the same way.
"Ah, sorry, sorry. I spaced out. You two have been training pretty well, haven't you noticed? You can both run across the water now. You're a match made in heaven." Hui spoke with a hint of apology.
He hadn't forgotten that his father had told him to keep it a secret. For now, he'd have to bluff his way out of it. Hui thought to himself.
Sure enough, as soon as Hui said that last part, the two went back to their usual routine.
Phew. That's done.
The masked ninja nearby couldn't help laughing at the kids staring at rocks for so long. Kids really were kids.
When it was about time to call it a day, Hui called the two of them back from the water.
"It's getting late. Let's continue training tomorrow. We've more or less gotten the hang of Water Walking, so tomorrow we'll practice climbing trees and walls. I haven't practiced that either, so I'll join you."
The three of them went home, and the masked ninja nearby breathed a sigh of relief.
Back home, Hui stared at the soup on the table as he ate.
What Father told me can't be wrong. But my chakra made more matter than my body weighs. That makes no scientific sense. Could I be special? Because of the thing on my back?
Hui's gaze slowly drifted, his thoughts wandering farther afield. There were plenty of Water Release users in the ninja world, and it seemed Earth Release had similar phenomena. It wasn't as if he were special.
How was he supposed to understand it using the methods Father taught him? When it came to understanding energy, he could find the answer from Father's hints.
Now he just didn't have a hint. He just didn't have a hint. Hui bit his lip, feeling like a complete failure.
It was such an obvious problem, yet he couldn't even come up with a way to explain it.
Chuanhe had thought Hui's expression looked strange, but as he watched him, he seemed to understand. Was he thinking about something? Good, good.
My teaching hasn't been for nothing. Yuki, do you see? It's not because I'm bad at teaching.
Time's gears kept turning. The food and soup on the table no longer steamed. Chuanhe didn't mind. He simply waited in silence.
At last, Hui's eyes brightened again. Looking at his father's smiling face across from him, he awkwardly scratched his head. "Sorry, Father. I was thinking about something just now."
"Oh? Tell me about it."
"Today I tested it, and it seems chakra doesn't follow the conservation of mass-energy."
"How did you test it?"
"I tried using the Water Ball Technique to make a huge Water Ball. In the end, the water I created had a greater volume than I did. Under normal circumstances, even if all the chakra in my body were converted into water at a one-to-one ratio, it shouldn't have that much mass."
"To test this phenomenon, I ran a small experiment. I compared two stones of roughly the same size. I soaked one with ordinary water and the other with water from a ninjutsu."
"I found that the water from the ninjutsu evaporated much faster than ordinary water. The difference was so great that I could rule out almost all outside interference."
"In the end, the mass of neither stone changed. Father, you said that matter can neither be created from nothing nor vanish into nothing. It follows the principle of conservation of mass-energy."
"So, as I see it, this proves that the conservation of mass-energy is wrong."
After hearing this, Chuanhe burst into laughter. Hui stared at his father, who was laughing so happily, completely at a loss.
Had I made some basic mistake again? Hui had checked the process several times. He couldn't be wrong.
Once he'd laughed enough, Chuanhe said, still smiling slightly, "No. The conservation of mass-energy still holds in this world."
Before you continue