Uesugi Sasuke's voice was not loud.
But in this courtyard, where even the wind seemed to have stilled, it rang out like thunder.
Every word struck the hearts of Jigoro Kuwajima and Zenitsu Agatsuma in the distance.
Qualifications?
Kuwajima looked at the mass of violent lightning in the boy's hand, and for the first time, his wrinkled face lost its composure.
It was not as though he had never seen a genius.
He himself had once been a genius who stood at the pinnacle of the Demon Slayer Corps.
He had also seen countless boys bearing debts of blood, who had devoted themselves to slaying demons for revenge.
But he had never seen anyone like Uesugi Sasuke before him.
Nor had he ever seen power so bizarre, so forceful.
That was not a Breathing Style.
Breathing Styles were powers humans squeezed from within themselves by tempering their bodies and imitating nature, so that their mortal flesh could stand against evil demons.
They were water, fire, wind, and thunder.
They were humanity's reverence for and imitation of nature.
But the thing in Sasuke's hand was not.
It was a form of creation.
A domain bordering on the "divine," in which one's own energy was forcibly distorted into a natural form.
This brat could actually create lightning out of thin air!
Turmoil surged through Kuwajima's heart.
As the former Rumble Hashira, his understanding of thunder had long since seeped into his very bones.
He could clearly sense that although the lightning in Sasuke's hand was unstable in form and violent in energy, its essence was pure to an outrageous degree.
And dangerous to an outrageous degree.
This power was like an untamed wild horse.
And this boy was a rider gripping its reins, liable to be dragged into the abyss at any moment.
Kuwajima's gaze returned to Sasuke's eyes.
What a pair of eyes they were.
They held none of the clarity a boy should have, nor any reverence before the strong.
Only bottomless darkness.
And at the heart of that darkness, a burning flame called revenge.
"Your sword is too sinister."
Kuwajima repeated those words once more, but his tone had changed.
It was no longer a simple reprimand, but carried a trace of gravity, and even a trace of regret.
He could see it.
This boy did not care whether he lived or died.
He only wanted to turn this power into the most efficient tool for slaughter.
If I refuse him...
Kuwajima could almost foresee this boy leaving with his incomplete power, then hurtling like an out-of-control meteor toward inevitable destruction as he burned himself away and destroyed his enemies.
That was not what Kuwajima wanted to see.
As a senior and a cultivator, he could not stand by and watch such a piece of uncut jade stray down the wrong path because no one had shaped it, ultimately destroying itself.
Teach him?
Kuwajima tightened his grip on his cane again.
That meant he would personally sharpen this deadly blade called "revenge."
He would have to take an enormous risk.
If this boy was devoured by his power in the future and fell into evil, then he, Jigoro Kuwajima, would be the one who had unleashed that evil demon with his own hands.
Only Chidori's piercing cries remained in the courtyard.
Sasuke's face had already grown somewhat pale.
His arm trembled slightly; maintaining this technique was clearly an immense burden on him.
Yet he still stood as straight as a javelin, using the last of his strength to uphold his pride and dignity.
Through his actions, he was telling Kuwajima.
This was his only bargaining chip.
And the entirety of his resolve.
A long time passed.
So long that even Zenitsu Agatsuma thought his master would refuse again.
At last, Kuwajima spoke.
"Put away your sorcery."
His voice was hoarse and weary.
At those words, the light in Sasuke's eyes flickered slightly, and the lightning in his palm dispersed.
An intense wave of weakness washed over him. He swayed, but forced himself to remain standing.
"I can teach you Thunder Breathing."
Leaning on his cane, Kuwajima walked back to Sasuke, one step at a time.
His single eye fixed on Sasuke.
"But I have my rules."
"First, under my tutelage, you are a swordsman before anything else. Until you learn to hold a sword, you are forbidden to use that dangerous power of yours again."
"Second, what I teach is a sword that protects life, not a butcher's blade to satisfy your desire for revenge. What you must learn is how to become a member of the Demon Slayer Corps, not a lone avenger."
"Third, and most importantly."
Kuwajima's tone grew sterner than ever before.
"If one day I discover that you have been beguiled by power and strayed onto an evil path, I will deal with my wayward disciple myself."
"Can you do that?"
He had not asked whether he was willing.
He had asked whether he could do it.
This was an order.
And a warning.
Sasuke fell silent for a moment, then slowly nodded.
"Yes."
One word.
Crisp and decisive.
This tense confrontation finally drew to a close.
Kuwajima let out a long sigh, as though he had made an exceedingly difficult decision.
He turned and shouted toward the peach tree that was still trembling.
"Zenitsu! Get over here!"
Zenitsu Agatsuma jolted and scrambled over, tear tracks still on his face.
"M-Master..."
"From today onward."
Kuwajima pointed at the expressionless Sasuke.
"He is your junior disciple, Uesugi Sasuke."
Zenitsu looked at the terrifying fellow before him, who had just been conjuring lightning in his hand, and opened his mouth. He felt as though his good days had come to an end.
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