No.
The thought screamed through Tanjiro's mind, a desperate denial against the horror unfolding before him. This isn't happening. My sister, Kamado Nezuko, is the kindest girl in the world. She would never hurt anyone! Even when she became a demon, she protected people. She wouldn't... she couldn't...
His memories of a gentle sister who cared for their younger siblings warred with the cold-eyed monster standing over his friends. As Tanjiro remained frozen in shock, Nezuko moved again.
There was a sickening crunch as she struck Zenitsu. His arm didn't just break; it exploded in a shower of blood and bone fragments, the force of the blow sending him flying backward. Blood gushed from Inosuke's wounds as he tried to defend himself, his twin blades proving useless against her blinding speed.
Even Akaza, who had been watching with casual indifference, seemed momentarily surprised by the display of raw power. A flicker of understanding crossed his face. He remembered being there when his master, Tsukihiko, had captured this girl. In the same instant, a silent command echoed in his mind, a direct transmission from Muzan himself: The girl will handle this.
Akaza's lips curled into a faint, cruel smile. This wasn't a simple battle; it was a performance. A psychological attack designed to shatter Kamado Tanjiro completely. The other fronts in the Infinity Castle were already under control; the Demon Slayer Corps was all but annihilated. This final act was purely for torment.
And it was working.
Tanjiro watched, his heart splintering. His kind, gentle sister had just crippled Zenitsu and gravely wounded Inosuke. Her attacks were impossibly fast; even with his Demon Slayer Mark active and his senses pushed to their limit in the Transparent World, he could barely follow her movements.
A surge of pure, undiluted hatred for Muzan burned through him, hotter than his own blade. This was his fault. This was what he had done. Tanjiro had joined the Demon Slayer Corps, endured hellish training, and fought countless demons for one reason and one reason only: to turn his sister back into a human. And now, that same sister was the monster he had sworn to destroy.
"Nezuko..." His voice cracked, a desperate, hopeless plea. "Nezuko, it's me! It's your brother!"
She didn't even flinch. As if his words were nothing but the wind, her figure blurred, vanishing from where she stood and reappearing directly beside Genya Shinazugawa.
"Damn it!" Genya swore, his finger already on the trigger of his firearm. He had seen what she did to the others and was ready to fire.
But he was too slow. Before his finger could tighten, a sharp, wet crack echoed through the room. His entire arm, gun and all, was torn from his shoulder. A shrill, agonized scream erupted from his throat as he stumbled back, clutching the bloody stump. He couldn't believe it. This was the same quiet, well-behaved girl he'd traveled with?
"Flower Breathing, Fourth Form: Crimson Hanagoromo!"
Kanao Tsuyuri finally made her move. She burst forward, her speed like lightning, her blade a graceful, flowing arc aimed at Nezuko's neck. Her movements were a beautiful, deadly dance.
But Nezuko was faster. In the instant before Kanao's blade could connect, Nezuko's presence simply… vanished. Her aura, her scent, every trace of her disappeared completely.
How is that possible? Kanao's eyes widened in astonishment. No matter how skilled a warrior was, they always left some trace of their existence, some faint disturbance in the air. But Nezuko was gone, as if she had been erased from reality itself.
"Kanao, be careful! Above you!" Tanjiro's warning roar came a second too late.
A thin red line appeared across Kanao's neck. For a moment, she just stood there, her pretty face frozen in surprise. The memories of her life, of her sisters at the Butterfly Mansion, of her time with Tanjiro and the others, flashed through her mind before everything went dark.
Her body fell to the ground with a soft thud. Deader than dead.
The air grew heavy, thick with a profound silence. Tanjiro felt as if he were standing alone in the deepest pit of Hell. In just a few moments, Nezuko had single-handedly defeated Zenitsu, Inosuke, and Genya, and had murdered Kanao right in front of him.
The grief was like a physical blow, but something else rose from beneath it: a burning, white-hot rage.
There was no need to focus, no need to consciously awaken his Mark, his Crimson Red Blade, or the Transparent World. They erupted on their own, fueled by pure agony. His own sister had not only become a true demon, but she had killed his friends, his comrades. This was something Tanjiro could not, would not, tolerate. He had cried while slaying other demons, feeling pity for the tragic lives they had lived before their fall.
But this? How could he pity this? How could he feel sorrow when the monster wearing his sister's face was the source of his deepest suffering?
He gripped the hilt of his Nichirin Sword so tightly his knuckles turned white. He could not endure it anymore. Even if the demon in front of him was his biological sister, his only remaining family, he had to make his move.
Just as he coiled his muscles to strike, a soft, familiar voice—a voice from his happiest memories—floated into his ear.
"Brother... are you going to kill me...?"
It was Nezuko's human voice, perfect and clear. For a heartbeat, Tanjiro froze, the sound shattering his resolve.
In that single moment of hesitation, she attacked. Pain exploded in his shoulder as a blood arrow shot from the wound. He had instinctively dodged at the last second; otherwise, his entire arm would have been torn off.
"Ahhh! AHHHH!"
A roar of pure, animalistic rage ripped from Tanjiro's throat. He was no longer thinking, no longer grieving. He was utterly and completely enraged.
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