That night, Jigoro Kuwajima could not sleep.
The old man sat beneath the dim lamplight, neither polishing his beloved Nichirin Blade nor mending his worn clothes.
He simply sat there in silence.
In his mind, that piercing birdsong echoed over and over.
Before his eyes, the image of that boulder reduced to dust scattered across the ground kept resurfacing.
He had seen countless prodigies.
Some had swords as swift as lightning; others had bodies as tough as steel.
But he had never seen anyone like Uesugi Sasuke.
That was not talent.
It was a power more fundamental, more ancient, and more... dangerous.
What Kuwajima feared was not the power itself.
What he feared was the vast emptiness behind it.
In those cold eyes, he saw only the flames of vengeance, without the slightest trace of human warmth.
This child was a blade of unparalleled sharpness.
But he had no sheath.
More frightening still, he had no hand holding his hilt.
He himself was that sword, existing only to kill.
A sword like that would ultimately meet only self-destruction.
Creak.
Kuwajima slid the door open and saw the lone figure in the courtyard.
Sasuke sat cross-legged in the moonlight, his hands forming hand seals as he practiced controlling his chakra.
Thin blue-white arcs of electricity danced at his fingertips like living things.
"Sasuke, come inside for a moment."
The old man's voice was a little hoarse.
Sasuke opened his eyes, withdrew his chakra, stood up, and walked silently into the room.
Kuwajima neither mentioned his secret Ninjutsu practice nor asked about the secret of that blood-red eye.
He simply poured Sasuke a cup of hot tea.
The fragrance of tea curled through the quiet room.
"Do you know when the Demon Slayer Corps was founded?"
Kuwajima spoke abruptly.
Holding his teacup, Sasuke did not answer, merely signaling with his eyes for him to continue.
"A long time ago. So long that even the history books have no detailed record."
Kuwajima gazed out the window at the night sky, as though looking through time.
"When I was young, I too thought becoming a member of the Demon Slayer Corps was about slaying every evil demon and making a name for myself."
"I once knew a comrade whose swordsmanship was mediocre and whose Breathing Style was a complete mess. But to protect a peasant woman behind him, someone he had never met, he used his own body to block an evil demon's fatal blow. He was still smiling when he died."
"I also knew a senior who had a chance to escape, but fought to his death holding back a powerful demon to buy an entire village time to evacuate. In the end, all people found was his broken sword."
Kuwajima's voice was level, as though he were telling stories about other people.
"They were weak."
Sasuke's icy voice interrupted the old man's recollections.
"If they had been strong enough, they wouldn't have had to die."
Kuwajima's body trembled slightly.
He turned his head and looked into Sasuke's utterly unruffled eyes.
He was not angry. He merely looked at him with something close to sorrow in his eyes.
"Yes, they were weak."
"But their swords had souls."
The old man spoke each word distinctly.
"Sasuke, let me ask you. What do you wield your sword for?"
"To kill demons."
Sasuke answered without hesitation.
"And then? Once you've killed all the demons, what then?"
Kuwajima pressed him.
Then?
Sasuke froze for a moment.
He had never considered that question.
In his world, there was only vengeance.
Killing all the demons and avenging his family-that was his entire reason for living.
As for afterward... he did not know, nor did he want to know.
"Remember this."
Kuwajima stood up, walked over to him, and placed his callused hand on Sasuke's shoulder.
"When you wield your sword, there should also be something behind you that you need to protect."
"A sword without a soul, however sharp, is only a weapon that harms others and its wielder alike."
Protect?
The faces of his parents before their deaths flashed through Sasuke's mind.
They had once been everything he wanted to protect.
But now, they were both gone.
How bitterly ironic the word "protect" was to him.
"I have nothing to protect."
He pushed Kuwajima's hand away, his voice as cold as ice.
"Very well."
Kuwajima nodded, seemingly having expected him to say that.
"Starting tomorrow, stop all training in Breathing Styles."
Sasuke's head snapped up, a fierce glint flashing in his eyes.
"You will have only one task each day."
Ignoring his gaze, Kuwajima announced calmly.
"Swing your sword one thousand times. When you understand what you wield your sword for, come to me again."
With that, the old man turned and went into the inner room, paying him no further attention.
Sasuke stood where he was, his fists unconsciously clenching.
Swing my sword?
What was the point of such time-wasting basic training?
He could not understand.
Yet his master's words, "A sword without a soul is only a weapon," were like an invisible needle, lightly pricking his heart.
Though the touch was light, it hurt deeply.
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