Sasuke stood in the courtyard, swinging a wooden katana in his hands. His movements were fast, sharp, precise, and controlled… until, suddenly, his stance shifted. The smooth grace of his swings suddenly became something clumsy, almost desperate, as if he were defending against blows no one else could see. If someone had been spying on him, they would have thought he was fighting a ghost.
For the last four days, ever since Nano Mashine had awakened within him, Sasuke had been pushing his body to its limits. The results amazed him. Tasks that once felt difficult now came easily. He was faster. He could leap higher. His strikes landed with greater force. Everything he once struggled with seemed trivial now.
He was in a state of ecstatic bliss. He would never have imagined himself growing so strong, so fast.
Then, a sharp pain struck his shoulder. He staggered, his concentration breaking, and the now-familiar voice echoed in his mind.
[Combat simulation has ended. Wounds sustained: 62%. Simulated enemy wounds: 2%.]
Sasuke collapsed to the ground, panting heavily. He had been practicing the Uchiha kenjutsu style, techniques he'd pulled from the clan library. Nano had fed the knowledge directly into his mind, teaching him the intricacies of its strengths and weaknesses. At first, he had struggled to adapt and use it, but as soon as he mastered the basics, Nano proposed something new.
The best way to advance was to fight against a simulated opponent, a swordsman with complete mastery of the Uchiha kenjutsu style.
Sasuke let out a long breath and finally pushed himself upright. He brushed dirt from his clothes, forcing himself to focus on the result.
'At least it's not eighty percent this time…'
The first simulation had nearly broken him. He'd felt like he was truly about to die, his body overwhelmed by the blows of the faceless figure. Nano had reassured him that fatal strikes were dulled not to hurt as much and that reaching one hundred percent wounds would end the simulation, but the pain still lingered vividly in his memory.
He looked across the courtyard. The faceless figure stood motionless, its chest bleeding glowing particles from the wound Sasuke had managed to inflict.
A small smile tugged at his lips.
'I injured you…'
Progress. Real progress.
His confidence swelled. He always knew he was talented, but he had never expected to advance this fast. Every time the battle ended, Nano fed him a detailed analysis of the fight, inserting the knowledge directly into his mind. Each correction, each adjustment, revealed how much more he lacked compared to his simulated opponent.
At first, Sasuke assumed the simulation would simply use the kenjutsu style exactly as he knew it, something he could exploit. But it was nothing like that. The faceless man fought like a warrior seasoned by decades on the battlefield. It adapted to his every move. It countered in ways he didn't think or expect it to. It knew its limits, and it wielded its strengths with ruthless precision while solely relying on the Uchiha style.
Nano had not exaggerated. This was a master of the technique.
Sasuke couldn't even rank it properly. At minimum, it fought like a skilled chūnin… perhaps even a jōnin. And the thought that it fought at that level without chakra… that made him smile again.
If he could defeat it, that would mean he had reached that strength, too.
[Would you like to continue the simulated combat?]
Sasuke hesitated. His body felt fine. Nano kept him at peak condition, ensuring he was never fatigued for long. But his mind… his mind was tired. The sun was setting, and exhaustion weighed heavily on him.
'Not tonight,' he thought. Although he didn't have to worry about not being in his best state when he met his jonin sensei, he also knew the importance of rest.
The simulation ended, and the figure vanished. He put the wooden katana back in its place and started walking back toward his home.
It was in these quiet moments that the images returned to him—the visions of the future. They gnawed at him, filling him with doubt.
'Nano.'
[Yes, Host?]
'Where do you come from?'
[Answering, I do not have data on my origin. I exist only to assist the Host to the best of my ability.]
Sasuke sighed. He had asked the same question a dozen different ways, hoping for a different answer. But always, the response was the same. He wasn't a fool. Whatever had granted him these abilities must have had its own purpose. He was certain it was connected to the future vision.
Nano itself had admitted the source was unidentified.
When he entered his house, silence greeted him. He removed his sandals, his eyes falling on the Konoha forehead protector resting nearby. His lips pressed into a thin line.
'Is it so wrong… to want the truth about this village? Is it so wrong to grow stronger? Do I really care where this power comes from?'
He shook the thought away.
'Nano. Insert the data from today's fight.'
The dizziness came quickly, but it was less intense than before. Suddenly, enlightenment washed over him. He had come to love that feeling, every mistake replayed in his mind, every flaw laid bare, and with them, the corrections.
[Analysis complete. Sufficient mastery achieved. Would you like to stimulate your muscles to match those of the simulated man? Caution: Doing so would bring your body closer to its current limit.]
Sasuke froze.
'What?'
[Would you like me to stimulate the Host's muscle groups to match those of the simulated opponent?]
Sasuke was sure he knew all the basic abilities Nano provided, but this was the first time he heard something like this.
'Explain. What does that mean?'
[Due to your advanced understanding of the sword techniques and the data I have collected during your sparing, the analysis of true Uchiha style kenjutsu mastery has revealed the precise muscle groups and bone structure required to perform at peak efficiency.]
'But… wasn't the simulated man already a master?'
[Correct. The simulated man was a master, but his physique was assembled through trial and error simulations to build the optimal muscle groups for the style, since I did not scan the body of anyone who uses the technique. With your progress, I have refined the analysis. What you fought before was close to mastery. Now, the true potential has been revealed.]
Sasuke was truly stunned.
So… the man he had been struggling against wasn't even using the style to its full potential?
'A-As expected of a Uchiha technique…even when it was not at its full power, it managed to overwhelm me.'
He tried to bury his embarrassment, remembering how proud he had been just to scratch that opponent. But another thought struck him, sobering him instantly.
Did that mean his next simulated opponent would be even stronger?
'Wait. Nano, why not just transfer the correct muscle structure instead of the optimal one?'
[That would push your body beyond its current limits. The risk of stunted growth and permanent damage is 93%. Recommended course: gradual optimization as you age.]
Sasuke sighed. 'Proceed when I'm asleep.'
[Understood.]
He stood up and made his own dinner.
Dinner was quiet, as always. He ate silently while thinking of the next step, cleaned, and went to bed.
'Ha… what a day,' he thought as sleep slowly pulled him under.
Then another question flickered into his mind.
'Nano… can the simulated man use the Sharingan?'
[Affirmative. Would you like it to use the Sharingan in your next spar?]
Sasuke let the words bounce around his head, then ignored them. He regretted asking the question at all; peace was already scarce, and he didn't need more nightmares tonight. He shifted in bed and let sleep take him.