The young man with golden hair was teleported onto a wide stone platform. He landed steadily, his expression calm—but his golden eyes locked instantly onto a familiar silhouette standing at the far end.
Zenitsu Agatsuma had arrived.
And waiting for him was none other than Kaigaku—his former senior brother, now a demon.
Zenitsu's eyes turned ice-cold. This was the man who had bowed before an Upper Rank demon, who had betrayed their master, Kuwajima Jigorou, and driven him to commit seppuku in shame. This man—this traitor—was no longer human.
Kaigaku slowly turned to face Zenitsu. His appearance was drastically different. Fangs jutted from his mouth, his ears were pointed, and his skin had turned a deathly pale. The whites of his eyes were now pitch black, his sclera bearing demonic tiger-like markings. Long black nails extended from his fingers, and he wore a black kimono tied at the waist with a shimmering blue sash.
> "I heard the old man died," Kaigaku said flatly. "Makes life a bit quieter."
His words were laced with venom and indifference.
Zenitsu's brow twitched, a vein popping on his forehead.
> "But you still look like trash," Kaigaku continued, sneering. "Long time no see, Zenitsu."
> "You haven't changed one bit—still short, still shabby, still pathetic. Tell me, do you even know any techniques besides Ichi-no-kata?"
Before Zenitsu could reply, Kaigaku vanished from his spot and reappeared in front of him in an instant, smirking.
> "So, can you even use Ichi-no-kata properly?"
Zenitsu didn't flinch. His voice was calm but biting.
> "Don't compare me to you, you piece of garbage."
Kaigaku's expression twisted. A vein pulsed on his forehead now.
Zenitsu's cold smirk deepened. He stared directly into Kaigaku's hateful eyes.
> "Don't you know, brother? Kibutsuji Muzan is about to die."
> "Once he's gone, all demons will perish. Including you."
> "No matter how desperately you cling to life, your cowardly betrayal won't save you from the fate that's coming."
Kaigaku's face contorted. He spat back.
> "Muzan-sama will not die. You Demon Slayers will be annihilated long before that happens!"
Zenitsu didn't bother responding. He simply reached for his swords—two golden Nichirin Blades gleamed as he drew them, electricity already crackling faintly around their edges.
> "That's why you won't live to see that day," Zenitsu said coldly.
> "You've always been a coward. A boastful, selfish coward. And you're just as pathetic now as you were back then."
Kaigaku let out a furious roar and unsheathed his own sword. While the shape mimicked a standard Nichirin Blade, this one was forged from his own flesh and blood. Its blade was a dark gold streaked with jagged lightning patterns. The hilt, white with a triangle motif, contrasted starkly with the black scabbard strapped at his side.
They charged.
The moment their blades collided, an explosive shockwave echoed across the platform. Zenitsu's right foot slid back from the sheer pressure.
Kaigaku's strength had skyrocketed after becoming a demon.
> "What happened to that big talk?" Kaigaku mocked as their swords clashed again and again.
The two brothers exchanged blows at blinding speed. In just a few seconds, they had already fought dozens of rounds. Sparks danced wildly with every clash, and the entire platform lit up from the thunderous light of their blades.
Though Kaigaku clearly had greater brute strength and speed, Zenitsu's defense was airtight. No matter how aggressive Kaigaku's attacks became, he couldn't break through Zenitsu's guard—and it was starting to infuriate him.
Then Kaigaku grinned. Black lightning began to crackle from his blade, filling the air with an ominous hum.
His Blood Demon Art had activated.
Unlike the golden lightning from Thunder Breathing, Kaigaku's demonic power transformed it into pitch-black electricity that inflicted lingering damage. It left lightning-shaped wounds, and the extreme heat scorched flesh from the inside.
Zenitsu didn't know the full extent of the ability, but he could instinctively feel the danger. Getting hit once might be enough to cripple him.
> "Thunder Breathing: Type Four—Far Thunder!"
Kaigaku became a blur of black lightning and shot toward Zenitsu. But in the same moment, Zenitsu's signature technique—Thunderclap and Flash—activated, turning him into a bolt of golden lightning that narrowly evaded the strike.
> "Speed like that still can't match Thunderclap and Flash," Zenitsu sneered. "You never could master it."
Kaigaku roared in frustration.
> "House Entrance!"
A massive wave of black lightning exploded outward from Kaigaku in every direction.
> "Thunder Breathing—Land Style: Lightning and Thunder!"
The dark, high-density slashes covered the battlefield like a storm. Zenitsu didn't block; instead, he retreated swiftly, dodging with expert precision.
Kaigaku grinned wickedly. His next technique was already on its way.
> "Thunder Breathing—Type Five: Heat World Thunder!"
From beneath Zenitsu, a massive bolt of black lightning exploded upward at a speed impossible to track.
BOOM!
Dust billowed into the sky. A crater formed where Zenitsu had just been. As the smoke cleared, Kaigaku's expression twisted in disbelief.
Zenitsu stood unharmed.
> "How… how is that possible?!"
Kaigaku couldn't comprehend it. A person mid-air shouldn't be able to dodge such an attack.
But Zenitsu wasn't ordinary anymore.
He had learned to see through the world.
He remembered James's words during their grueling training.
During one of their many failed attempts to turn Zenitsu's blade red, the golden-haired boy had been frustrated and restless.
> "There's no need to fixate on the sword turning red," James had said, patting Zenitsu's shoulder gently.
> "I know you're angry. I know you're hurting. But this obsession won't bring him back."
Zenitsu had just lost someone dear, and his thirst for revenge burned brightly.
At the time, James hadn't taken Kaigaku seriously. After all, with James's strength, the Upper Ranks were no longer much of a threat—and he had assumed Kaigaku would never cross paths with someone like Kokushibou.
But fate had taken a different route. Kaigaku had encountered Muzan instead.
James had crouched next to Zenitsu, casually speaking as they watched others train.
> "You know what matters most when you're moving at high speed?"
Zenitsu had tilted his head.
> "Stamina?"
James shook his head, smiling.
> "Nope. A great ninja once said—dynamic vision. You need to see everything clearly while moving fast."
Zenitsu had blinked in confusion.
> "Speed is only useful if you can control it. And if you can control it precisely—while seeing everything? You become invincible."
Those words still echoed in Zenitsu's mind.
Now, standing before the monster that his brother had become, Zenitsu felt sorrow—deep, aching sorrow. No matter what had happened, they had once shared time together. He had admired Kaigaku once. He had dreamed of standing beside him.
> "I'm sorry... Brother."
Electricity sparked around Zenitsu. His breathing synced perfectly with the thunder surging through his body.
> "Another flashy move? I've had enough of your—"
Kaigaku never finished the sentence.
Zenitsu vanished.
The speed was incomprehensible—even to Kaigaku's demon-enhanced senses.
He appeared like a thunder dragon in motion—unstoppable, precise, divine.
> "Thunder Breathing—Seventh Form: Flaming Thunder God!"
With the transparency of the world guiding him, Zenitsu could adjust mid-strike, aim for the neck with surgical precision.
SHRING!
A single flash of golden lightning lit the air.
Kaigaku didn't even know what hit him.
Pain exploded in his neck. His vision blurred.
> "You..."
He barely croaked the word before his head was severed cleanly.
Thud.
His head hit the ground with a dull sound.
Zenitsu stood behind him, blades lowered. His eyes were filled with tears.
> "Grandpa… I'm sorry."
The storm had passed.
But Zenitsu's heart still thundered in grief.
Øóffer going on for diamond tier
pàtreøn (Gk31)