Sign-In System: One Piece, Demon Slayer & Beyond

Night had fallen.

The moon was veiled behind clouds, and stars barely dotted the sky.

Darkness cloaked the entire town.

Given the disturbing events that had taken place recently, no one dared linger outside. Doors were shut early, windows bolted tight, and the streets were eerily deserted—an oppressive, unsettling silence settling over everything.

In a narrow alley in the southern part of town...

A grotesque figure emerged from the shadows—a creature vaguely human in shape, but horribly distorted. Its legs were short and stubby, while its arms were abnormally long and slender. In each hand, it gripped a short-handled scythe attached to a chain. Its emerald, slit-pupiled eyes gleamed with cruelty and hunger.

It locked eyes on a nearby house with warm lights still flickering through the windows.

The demon licked its lips.

A string of thick, sticky saliva dribbled past its jagged, venomous-looking teeth, making its already nightmarish appearance all the more terrifying.

At that same moment...

Three members of the Demon Slayer Corps, stationed on the rooftop at the very center of town, instantly sensed the shift.

"It's here."

"South side."

"Stick to the plan."

"Understood!"

With just a glance between them, the two men and one woman nodded with resolve. Then, with a burst of movement, they launched off the rooftop and darted swiftly toward the southern district, their figures blending into the night.

By the time they arrived...

The courtyard of a small household lay in ruins. The owner of the house was slumped in the corner, blood trickling down his forehead—unconscious or possibly dead. His wife lay beneath the eaves, completely still, likely passed out from fear or pain. The demon, now in the midst of its evolution, had seized a young boy and was preparing to flee.

The short-haired slayer—Shuichi—took one look at the scene and exploded with rage.

"Put him down—NOW!"

With a sharp shing, he drew his Nichirin Blade, and with a flash of flame at his heels, launched toward the demon like a roaring inferno.

"Shuichi, wait!" the tall slayer called out, too late to stop him. He turned to the woman beside him. "Yukita, provide cover!" Then he too unsheathed his sword and charged forward.

Shuichi, a user of Flame Breathing, gripped his sword in both hands. The blade shimmered with a faint, fiery glow as he unleashed a wide, sweeping arc—his blade slicing through the dark like a blazing crescent—aimed directly at the demon's face.

Clang!

The demon raised one of its scythe-like arms and took the blow head-on without budging.

Shuichi's expression darkened.

Just as I thought... it's gotten stronger!

In the next instant—

The other scythe in the demon's right hand twisted violently. The chain coiled like a viper, the spiked tip hissing through the air, aiming straight for Shuichi's forehead like a venomous fang.

In that split second—

CLANG!

Another Nichirin Blade sliced in from the side, intercepting the attack with a crisp, ringing clash.

The tall slayer had arrived just in time, his blade knocking the chain aside with a clean, powerful strike.

Shuichi used the opening to retreat a step and regroup at his companion's side.

"You alright?"

"I'm good."

They exchanged a quick nod.

Then, without hesitation, they both launched at the demon again—one attacking from the left, the other slashing in from the right.

Caught off guard by the coordinated assault, the demon staggered.

Unable to fend off both sides simultaneously, it was forced to release the boy.

Seeing his chance, the tall slayer lunged forward and caught the falling child midair, then shouted as he tossed him toward their teammate. "Yukita! Catch!"

"Got him!" Yukita called back, reaching out just in time to cradle the boy safely in her arms.

Now that the child was out of danger—

Shuichi and the tall slayer pressed their attack harder than ever.

Blow after blow, they drove the demon back, forcing it into retreat.

The tall slayer's movements became faster, more fluid—waves of attacks rolling out like crashing tides as his Nichirin Blade sliced through the night.

The demon flailed its long, muscular arms, its dual scythes creating a deadly storm of spinning steel, forming a tight web of defense that barely held against the onslaught.

But in doing so—

It had completely exposed its back.

The female slayer saw her chance.

She slipped behind the demon in an instant and drove her blade forward.

Three-fold Piercing Strike!

With a sharp whoosh, her Nichirin blade burst three blossoming blood flowers across the demon's back.

The sickle demon howled in pain, its grotesque face twisted skyward. With a furious bellow, it swung its unnaturally long and muscular arms backward with a whistling crack.

The girl leapt high just in time, narrowly avoiding the devastating blow.

The wall behind her wasn't so lucky—shattered on impact like paper.

"Shuichi, now!" the tall male slayer shouted.

In the next instant, Shuichi—already airborne—came into view.

Body tilted in midair, his flaming Nichirin blade crackled with power, fully charged.

"This will be the final blow!"

"Sunset Sky Slash!"

His blade, engulfed in flame, arced down like a falling star toward the demon's exposed neck.

It should have been a clean cut. A fatal one.

But at the very last moment—

Pop!

Two bulbous growths under the demon's armpits burst open, revealing two bizarre, sinewy arms that shot out like vipers.

In the blink of an eye, one of the freakish limbs slapped Shuichi's sword sideways, knocking it clean out of his grip.

"What?!" Shuichi's eyes widened in shock.

Before he could react—

The other elongated arm came crashing toward him like a whip.

WHACK!

The blow struck him squarely in the chest and sent him flying like a broken ragdoll. He slammed into a nearby wall so hard, the surface cracked and caved in, embedding him halfway inside.

"Gah!" Shuichi coughed a mouthful of blood. Agonizing pain from shattered bones screamed through his body. The world spun.

He forced himself to look up—vision blurred, body limp.

There it stood, no longer just a demon, but a terrifying anomaly—a sickle demon now bearing four massive arms, its sickles gleaming, its aura drastically different from before.

"A… Mutant Demon…"

Blood dripped from his lips. His voice, faint and fading, carried toward his teammates.

"Run… ru…n…"

"Shuichi!"

The female slayer—Yukita—cried out in anguish.

No reply came. His eyes fluttered shut.

"He evolved…"

The tall slayer stared at the four-armed abomination, his grip on the Nichirin blade trembling, cold sweat beading on his brow.

"And he did it mid-battle. He was faking weakness… just to lure us in?!"

His heart sank.

Mutant demons weren't just stronger—they were on a whole different level.

There was no way the three of them could win. Not against this.

The sickle demon's front arms twirled its sickles in a deadly dance, while its rear arms gripped the chain-tails with eerie precision. Its emerald slit-eyes curved into wicked crescents as it chuckled with a grotesque, gurgling sound.

"Khihaha… hihihihi… glurg…"

The two remaining slayers stared at it, their hearts gripped by ice-cold dread. The same demon that once cowered in their presence now loomed over them, exuding overwhelming bloodlust.

"W-What do we do now?" Yukita whispered, her voice shaking.

"I'll hold it off," the tall slayer said, stepping forward. "You run and inform Lady Shinobu—now!"

Yukita's eyes widened. She could see it—his hands were trembling.

"GO!" he roared.

Tears welled in Yukita's eyes.

She knew. He knew.

Facing a mutant demon alone… it was suicide.

"…None of you are getting away."

The sickle demon grinned. It had heard everything.

Its newly-grown arms shot forward like spears, slicing through the air with a sonic boom, lashing down at the two slayers.

They dodged—barely.

The ground where they stood moments ago exploded into rubble. A regular human would've been obliterated on impact.

"Move, dammit! Or do you want us all to die here?!"

The tall slayer, usually calm and composed, now bellowed with fury at Yukita.

Then—CRACK!

One of the long arms whipped toward him at lightning speed.

He had no time to dodge.

Gritting his teeth, he swung his blade to intercept.

CLANG!

The arm struck with such force that the Nichirin blade shattered mid-air.

The impact hurled him backward like a bullet, slamming through the courtyard wall and into a shadowy alley beyond.

Yukita, just about to leap over the wall, was struck by the follow-up strike.

She crashed to the ground hard, coughing up blood.

"Khihihi… gahahaha… glurg…"

The sickle demon stalked through the crumbled wall, stepping into the dim alley where the two injured slayers lay crumpled and bleeding.

Its emerald eyes gleamed with triumph and malice.

"The Demon Slayers… so much for your reputation."

"I wonder… do you taste any different from ordinary humans?"

The sickle demon licked its lips, a string of sticky saliva dripping down its chin.

It stepped forward, inching closer to the two wounded Demon Slayers.

Their eyes were filled with despair.

Just as the sickle demon raised its weapon, preparing to cleave them both in half—

The air shifted.

The temperature around them dropped sharply.

A chilling breeze swept through the alley, coiling around the demon like an unseen predator.

Frost suddenly began forming over the sickle in its hands, thin and white at first, then quickly thickening. Its swinging arms, once swift and deadly, slowed… and then stopped entirely.

The frost crept further, slithering up from the sickles to its grotesque limbs, freezing them solid in seconds.

"W-What the hell?!"

The sickle demon's eyes went wide in disbelief, its twisted face full of shock.

The two Demon Slayers, who had already given up hope and prepared for death, could only stare in stunned silence as they watched the demon's four limbs become bound in shimmering frost.

Ice?

But… it was July.

Step. Step. Step.

Footsteps echoed outside the narrow, dim alleyway.

In the stillness of the night, they sounded crisp—eerily loud.

All three—two humans and one demon—turned their gazes toward the sound.

A calm voice drifted to the ears of the two bloodied slayers, like a gust of winter wind cutting through summer heat.

"Demon Slayers… and you couldn't even take down this thing?"

"T-This thing…?"

Both the tall male and the female slayer blinked in confusion.

But they weren't the only ones reacting.

The sickle demon's vertical pupils contracted.

It sensed something—an overwhelming danger.

Without hesitation, the bizarre arms under its armpits—those muscular, root-like limbs—lashed out toward the voice at terrifying speed.

They cut through the air like spears of death, targeting the mysterious newcomer.

The Demon Slayers hadn't even processed what was happening.

The next second, those clawed arms glinted in the moonlight and were already inches from tearing into the silhouette standing at the end of the alley.

Ready to rip him open from chest to gut.

But—

"You strike first? Bold."

The voice was young. Calm. Even amused.

"Shame you're too weak."

From within the shadows, a single finger reached out.

HUM!

A ring of icy blue energy pulsed from the fingertip, rippling outward like water.

The charging limbs froze midair—literally.

Starting from their razor-sharp claws, a thin layer of ice began spreading outward in an instant.

The frost didn't stop.

It crawled along the length of the demon's arms, devouring flesh, muscle, and bone, racing toward the rest of its body.

The sickle demon, eyes wide with panic, realized what was happening.

With a shriek, it raised its cleaver-like weapon and hacked off both mutated arms at the shoulders, severing them in one brutal swing.

CRACK!

The frozen arms shattered like glass.

A thousand sparkling shards scattered into the air, falling like snowflakes under the dim moonlight.

The two Demon Slayers watched the scene unfold with blank expressions, their minds struggling to comprehend what they'd just witnessed.

W-What just happened?

Above them, the thick cloud cover shifted, allowing a sliver of moonlight to pierce through the alley's darkness.

That faint light illuminated the one standing calmly in the alley's mouth.

A tall young man, garbed entirely in black.

His posture was upright and composed, his face sharp and strikingly handsome.

In one hand, he casually held a silver-blue gourd, its surface faintly glowing.

His other hand remained extended, a single index finger pointing forward—thin wisps of white mist still curling from its tip.

He looked at the sickle demon, now reduced to two limbs, its aura greatly diminished, and its face twisted in fear.

And then he smiled.

A smile that chilled deeper than the frost.

"So…" he said gently.

"How do you want to die?"