"Shadow Clone Jutsu!"
A few days later, on a school holiday, Kairi adjusted his condition to its peak before beginning the hand seals. As he formed the standard eight signs with precision, a puff of white smoke rose beside him.
"Hello, original me," said the newly formed clone, greeting Kairi with a grin.
"Hey," Kairi replied, nodding in return. He quickly assessed his chakra and let out a breath of relief. As expected, the baseline chakra consumption for a single Shadow Clone wasn't particularly high. At this rate, he could probably create up to three clones at most.
But that was the limit.
After creating even one, his remaining chakra dropped to just over twenty percent barely enough to use any basic jutsu. And as for the clone, its chakra was so minimal that even performing basic ninjutsu would be impossible. The moment it tried, it would likely vanish due to chakra depletion.
Still, even though he had anticipated this, Kairi held a deep respect for this famed jutsu, known for its tremendous chakra demands. Even though he had technically already mastered it, he waited until his condition was perfect before attempting it. After all, using it recklessly could lead to serious consequences.
At worst, a failed attempt might leave him mentally disoriented. At worst, unconscious.
But based on his recent studies, Kairi was confident his chakra reserves were sufficient.
After all, chunin in the original story could use the Shadow Clone Jutsu without issue. Kairi might not have a chunin-level chakra pool, but Iruka had once said that the maximum chakra he could extract in a single pull was already close to that level.
And it wasn't like chunin typically stored chakra in advance before using Shadow Clones. So if they were using it in real time, Kairi figured he could handle one clone safely.
Still, nothing was guaranteed. To minimize risk, he waited for a day off and made sure he was well-rested and fully recovered before attempting it. And judging by the result, that had been the right call.
Kairi gave the clone a nod. A moment later, the Shadow Clone dispersed.
He frowned slightly.
He had intended to have the clone do the household chores before dispelling, not vanish immediately. Of course, he wasn't trying to exploit the clone. It had been a planned experiment.
And now, he had results.
A clone inherits the exact mental state of its caster at the moment it's created. Any thoughts Kairi had afterward were not transferred. The clone could make educated guesses after all, it shared his mind but it wouldn't know for sure what Kairi wanted unless he'd been thinking it clearly at the time of creation.
Aside from that, the chakra used to form the clone had returned to him but slightly reduced. According to what the clone had perceived of its own chakra reserves, it had started with more than what returned. This meant that not only did clones consume chakra to maintain their form, but a small portion of chakra was lost during the return process as well.
Still, that was within Kairi's expectations. The loss was likely proportional to the distance or time involved, and he wasn't planning to send his clones far, so the cost was acceptable.
But a question lingered in his mind: what would happen if a clone completely exhausted its chakra? Would its memories still return?
After all, memory couldn't transmit out of thin air it had to ride on chakra as a medium to return to the original body.
Kairi had considered this before. But now, after using the technique himself, he felt he had the answer.
Since a Shadow Clone is a physical clone, its creation relies on chakra a fusion of physical and spiritual energy. The body comes from physical energy, and its thoughts from spiritual energy. It made sense.
Upon dispersal, both forms of energy would recombine into chakra and return to the original. So even if a clone used up all of its chakra, it could still relay its memories when its form collapsed.
However, that led to a new idea. If you somehow trapped a clone in a place where chakra couldn't transmit, would that block the memories from returning as well?
Kairi shook his head. It made theoretical sense, but had no practical value. First, where would you even find or create such a place? And even if you could, the clone would likely notice something was wrong and dispel itself before being cut off entirely.
Now came the real test.
Kairi extracted the rest of his remaining chakra and once again formed the eight hand signs. This time, he didn't bother with compression or efficiency. He wasn't planning to use this clone in battle. As long as the jutsu activated, that was enough. After all, there was only so much mental focus to go around. He'd rather save his energy for training that would directly improve his combat strength.
"Shadow Clone Jutsu!"
The technique succeeded once again.
This time, the clone immediately walked over to the desk and began studying flipping through textbooks and going over the ninja scrolls Sina had given him earlier.
As for Kairi himself, he didn't assign himself any training. He needed to evaluate the clone's lifespan and measure the amount of fatigue returned when it dispersed. If he pushed himself too, his body might not be able to handle the accumulated fatigue when the clone ended.
Still, doing nothing felt wasteful. After a quick glance around the house, he decided to do a bit of light cleaning. It wouldn't drain much energy.
An hour passed. Kairi glanced at the still-active clone and was a bit surprised. Its duration was longer than expected. Even though the clone hadn't used any chakra, its mere existence still consumed a small amount. But apparently, the passive cost wasn't too high. This was promising.
A little while later, the clone looked up and spoke. "Ready, original."
After making sure Kairi had sat down on the bed, the clone watched him for a moment, then finally ran out of chakra and dispersed.
In the blink of an eye, a flood of memories and accumulated mental fatigue surged into Kairi's mind. He faltered slightly under the sudden impact but recovered quickly.
And the first thing he muttered was:
"Uzumaki Naruto… is insane."
He finally understood why Naruto was the only person who dared to use dozens or even hundreds of Shadow Clones to train.
For normal people no, for anyone not named Naruto it was simply unsustainable. Even the rest of the Uzumaki clan probably couldn't handle it. Maybe one or two clones for training, sure. But dozens? Hundreds? That was suicide.
When a Shadow Clone disperses, all the physical and mental exhaustion it experienced is transmitted back to the user. Which means the original body has to endure the combined fatigue of however many clones were active and all in an instant.
Kairi scratched his head and tried to think of a metaphor.
It was like lifting dumbbells for two hours using a weight you were comfortable with. You could manage that. But now imagine trying to lift hundreds of dumbbells all at once. The effect might be the same, but could your body even bear it? Could you handle being crushed under all that weight?
That was the difference.
Thinking back to how Naruto had trained for the Rasenshuriken, Kairi could only shake his head. Only Naruto could've pulled that off. Anyone else would've needed a body on par with a Sage's to survive the aftermath.
Still, Kairi felt all right for now. His clone had only been studying, not fighting, so most of the exhaustion was mental. His body could handle the transferred physical fatigue. As for the mental side…
That was Kairi's greatest pride. It was the one real edge he had.
This was why he had wanted to master the Shadow Clone Jutsu in the first place. It might not be flashy or powerful in battle but it was perfect for him. He had the mental resilience to endure the fatigue and the will to use it wisely.
He even felt like he could handle one or two more clones at the same time, but unfortunately, his chakra simply wasn't enough.
And this was only the beginning.
Kairi's eyes flickered with anticipation. The results of this experiment were almost perfect. Choosing to invest in the Shadow Clone Jutsu had definitely been the right move.
He already had some more advanced ideas but with his chakra drained, they'd have to wait a while longer.
After all, he still couldn't afford even a single soldier pill.