Hellish training and a genius who didn't belong

The days passed in this monotonous, repetitive cycle, filled with frustration.

Uesugi Sasuke's life had been reduced to three things.

Eating, sleeping, and training.

Jigoro Kuwajima's training methods were simple and brutal in the extreme.

Before dawn each day, they had to run laps around the entirety of Mount Momoyama carrying weights, until the last ounce of strength had been wrung from their bodies.

Next came thousands of basic conditioning exercises: push-ups, sit-ups, squats... Sweat soaked their clothes, then dried in the mountain wind, leaving a white crust of salt.

Finally came sword swings.

From sunrise to sunset, a thousand times, two thousand times, three thousand times.

Their arms went from aching to numb, until they seemed no longer to belong to them, repeating the slashing motion over and over on instinct alone.

For Zenitsu Agatsuma, this was nothing short of a living hell.

"I'm going to die! I'm really going to die!"

"My arms are going to break! Is that old man a devil?!"

"Waaah... I want to go down the mountain... I want to marry a cute girl and live out an ordinary life. Why do I have to suffer like this here..."

His wails had practically become Mount Momoyama's daily background music.

And what answered him was always Jigoro Kuwajima's merciless cane and furious roars.

"Shut up, you useless fool!"

"You can't even endure this much hardship, and you want to become a Demon-slaying swordsman? Get off this mountain!"

Whenever that happened, Zenitsu would cling to Kuwajima's one remaining leg, his face streaming with tears and snot, sobbing that he would never do it again.

Sasuke turned a blind eye to it all.

There was no room for crying or complaining in his world.

His system-enhanced physique allowed him to complete every exercise without expression, with perseverance far beyond Zenitsu's.

He was like a precise, cold machine, executing every programmed instruction.

Yet that sense of physical superiority vanished the moment he picked up a wooden sword.

"You idiot! Your shoulders are too stiff!"

"Your waist! Use your waist to generate power! Are you just hammering the sword down with your arms?"

"Your wrists! Relax your wrists! You're wielding the sword, not the other way around!"

Nearly half of Kuwajima's roars were directed at Sasuke.

He couldn't understand it.

He clearly possessed dynamic vision and learning abilities far beyond those of ordinary people, so why couldn't he perform even the simplest sword swing properly?

His body was accustomed to the lightness of a kunai and the directness of Taijutsu.

With an extension like a sword, he could never find that feeling of being one with his weapon.

Every swing he made bore traces of calculation and imitation, contrived and utterly stiff.

Yet Zenitsu, that cowardly, useless fool.

He closed his eyes every time he swung, looking as though he was about to burst into tears.

But the slashes he casually delivered always carried a natural sense of coordination.

Power rose from the soles of his feet, passed through the twisting of his waist and abdomen, and traveled along his arms to the tip of his sword, tracing a perfect arc.

Every single time.

"Do you see that, Sasuke?"

More than once, Kuwajima pointed at Zenitsu and spoke sternly to Sasuke.

"This is talent. Your bodies are naturally better suited to holding a sword than other people's. Yet you, with all your strength and willpower, are like a stubborn stone."

Sasuke said nothing, only tightening his grip on the wooden sword.

For the first time, he felt an emotion called jealousy toward someone he looked down on.

Why?

He couldn't understand.

He didn't know how long those days continued, but when Sasuke could complete five thousand sword swings without his expression changing, Kuwajima finally called an end to the hellish physical training.

He summoned both disciples to the training hall.

"Starting today, I'll teach you the fundamentals of Thunder Breathing."

The old man's expression was more serious than ever before.

Fear appeared on Zenitsu's face, while a flicker of anticipation passed through Sasuke's eyes.

"A Breathing Style isn't as simple as breathing through your mouth and nose."

Kuwajima spoke slowly, his voice low and powerful.

"You must breathe through the skin of your entire body, through every pore. Feel the air flowing inside you, and let oxygen flood every corner of your blood."

"When you truly master it, you'll feel every beat of your heart thunder like a drum. Every surge of your blood will be like lava."

"Your bodies will surpass human limits and gain the strength to contend with Demons."

Kuwajima's description brimmed with power.

But to Sasuke, it was utterly abstract.

Feel?

He was accustomed to using the perspective of chakra to "observe" and "control" the flow of energy in his body.

This explanation that relied on "feeling" left him at a loss.

"Now, close your eyes and feel it with your heart."

Kuwajima guided them.

Zenitsu nervously closed his eyes. Before three minutes had passed, steady snores rose from him.

He had actually fallen asleep.

Veins bulged on Kuwajima's forehead in anger, but in the end, he sighed helplessly and left him undisturbed.

Meanwhile, Sasuke's brows were tightly furrowed.

He sat cross-legged, his mind intensely focused.

He tried to understand it in his own way.

He sank his awareness into his body to "see" his blood flowing and "hear" his heartbeat.

He tried to accelerate that process through sheer willpower.

But he failed.

His body was like a meticulously fitted precision instrument. No matter what commands he issued, it operated only according to its established patterns.

He couldn't feel that sensation of "blood like lava" at all.

Time ticked by, second by second.

Sweat seeped from Sasuke's forehead.

Not from exhaustion, but from an agitation unlike anything he had ever experienced.

He felt as though an invisible, intangible wall stood between him and this world's system of power.

Yet Zenitsu, sleeping so soundly that he was drooling, unconsciously let out a short, faint breath in his dream.

At that instant, an almost imperceptible flicker of electricity seemed to flash through his golden hair.

Kuwajima saw it all.

And Sasuke, with his mind intensely focused, sensed it too.

He abruptly opened his eyes and looked at Zenitsu.

His gaze was filled with incomprehension, and a trace of loneliness even he had not noticed.

He stood on this mountain covered in peach trees, with his master and senior fellow disciple beside him.

Yet he felt that he had always been nothing more than an outsider.

A lonely soul who didn't belong, carrying the flames of revenge.