Worse Than A Demon? (Sasori x Demon Slayer)

鬼滅の刃 | Demon Slayer: Kimetsu no Yaiba (Anime) Naruto (Anime & Manga)
Gen
G
Worse Than A Demon? (Sasori x Demon Slayer)
author
Summary
In the midst of the Fourth Great Ninja War, Sasori of the Red Sand met his demise at the hands of Kankurō. Just as the final moments of his life slipped away, Sasori’s consciousness was pulled into a realm beyond imagination—a world where the rules of survival are rewritten.Sasori awakens in the world of Demon Slayer, a place unlike the shinobi battles he knew. Here, demons lurk in the shadows, and warriors wield strange techniques to slay them. Thrust into this unfamiliar reality, Sasori must quickly adapt to its new dangers and foes.Armed with his cunning intellect and mastery of puppetry, Sasori sets out to navigate this mysterious world. But survival is not enough—he is determined to carve his own path, leaving a mark on this realm of demons and demon slayers, just as he did in his own.
Note
-Author's Notes-English is my second language please do tell me if I make a mistake.
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Shadows of Humanity

Sasori's grip on the situation tightened, his focus sharp as he observed the demon's hesitation. It spoke volumes. Was the child important to this creature? The way it froze, its rage suddenly muted by fear, answered that question clearly. A glimmer of amusement flickered in Sasori's eyes.

Even if the demon hadn't stopped, it wouldn't have posed much of a challenge for him. But now that it had hesitated, Sasori knew the truth: the child mattered.

And that truth... was worth exploiting.

"Perfect," Sasori mused darkly, his blade still pressed against the child's neck. "Now... Tell me why you care."

"HE DOESN'T NEED TO TELL YOU SHIT!" The shriek came from below, as two massive claws shot from the ground, aiming to tear Sasori to pieces. But in a single fluid motion, Sasori shifted his blade, redirecting the strike just in time to block the claws—his sword a steady wall, preventing them from reaching their target.

The former Upper Moon Four seized the opportunity, the scales on his left arm shifting as his body coiled, moving with unnatural speed. His right arm morphed into a jagged, razor-sharp blade, slashing at Sasori from the side. The demon's movements were swift and precise, but Sasori, with a flick of his wrist, caught the attack mid-swing.

The blade bit into his arm. Sasori smirked, unphased by the cut. "Didn't think you demons were smart enough to work together," he remarked coolly, the amusement in his voice thick with mocking praise.

With a sharp twist, Sasori seized the demon's blade-arm, lifting it effortlessly. He spun the creature around, using its momentum to hurl its massive form into the mole demon. The collision sent them both crashing through the cabin walls and into the dirt outside with bone-shaking force.

Sasori stepped through the newly made hole in the wall, leaving the child behind without a second glance.

The mole demon and the former Upper Moon Four rose to their feet, brushing off the debris.

"Now tell me," Sasori demanded, his curiosity betraying his usual calm.

"WE AIN'T TELLING YOU SHIT—" the mole demon snapped, her voice brimming with anger, but the former Upper Moon raised a hand, silencing her immediately.

"There's no reason for us to fight," the scaled demon began, his tone measured and deliberate.

Sasori raised an eyebrow, his expression darkening. "Oh? And why is that?" he asked, his tone laced with sarcasm.

"Because we don't want Muzan alive any more than you do," the former Upper Moon declared, his voice steady.

"The demon lord? You're trying to kill him?" Sasori asked, his voice shifting to its usual cold and calculating tone.

"Yes," the scaled demon confirmed. "So, there's no reason for us to be enemies."

Sasori's lips twitched into a mocking smirk. "Fine. Then answer this... why do you have a human child?"

The former Upper Moon's gaze hardened. "The child... he will be the one to kill that coward Muzan. I will train him. Raise him. Prepare him to bring an end to the Demon King's reign." His voice carried a weight of unshakable determination.

Sasori chuckled softly, a dark amusement flickering in his eyes. "What a shame~ I was worried Muzan might actually be a threat, but he can't even keep his own demons under control? That's just pathetic." His laughter grew, a chilling sound that made the mole demon shudder. The former Upper Moon, however, remained impassive.

"Ha. Alright, you've convinced me," Sasori said at last, feigning nonchalance.

The mole demon and the former Upper Moon began to relax—only for Sasori's expression to twist into something far more sinister.

"But you'd be much more useful as part of my collection than raising some kid," Sasori continued, pulling out a scroll from within his cloak. The air grew tense again, the demons bracing themselves for whatever he intended.

"Your... collection?" The former Upper Moon Four, asked, suspicion heavy in his voice.

"Yes," Sasori replied with a sinister smirk, unfurling the scroll in his hand with deliberate care. The parchment seemed alive with menace, its inscriptions glowing faintly. "Tell me, former Upper Moon Four~ what's your name?"

"Tenshu..." the demon said, his voice low and steady, but his eyes burned with cautious defiance.

"Hmm... Tenshu," Sasori echoed, rolling the name across his tongue as if testing its flavor. He smirked again, dismissively. "Doesn't quite roll off the tongue. Oh well, I'll rename you after I claim you."

With that, Sasori pressed his palm against the scroll, and a thick plume of smoke erupted, enveloping the clearing. When it dissipated, Sasori's puppets stood in a menacing formation, their eerie, humanoid forms hovering like angels of death, each one radiating an unsettling aura.

Tenshu exhaled a long, weary sigh, his gaze steady despite the scene before him.

"What the hell is that?!" the mole demon shouted, her voice trembling with panic as she took in the sight of Sasori's army.

Sasori's puppets moved as if alive, their forms glowing faintly under the moonlight, their cold, wooden faces staring down at their foes like judges of a doomed world.

"Misa," Tenshu said, his voice firm and commanding, "get the child and leave. I'll handle this."

Reluctantly, the mole demon now identified as Misa, nodded, her claws tearing into the earth as she began to dig, preparing an escape route.

Sasori flicked a single finger, sending Ren, one of his puppets, streaking after her like a hunting falcon.

Tenshu moved instantly, positioning himself between Ren and Misa. The scales on his arms shifted like living armor, flowing and reshaping until each arm bore a long, gleaming blade. He slashed at Ren with inhuman precision, aiming to cleave the puppet in two.

But before the strike could land, two other puppets, Jiro and Taro, darted forward, intercepting the attack with their own weapons, creating a loud clash of metal and wood. Ren used the opportunity to slip past Tenshu, his dual blades flashing as he prepared to pursue Misa.

Tenshu's armor reacted instinctively, the scales along his back rippling downward to form a sharp, scorpion-like tail. The tail lashed out at Ren, aiming for his back, but Ren spun in midair, crossing his dual blades to block the attack just in time.

Sasori saw his chance. With a flick of his fingers, he sent Taro rushing behind Tenshu. The puppet's tanto blade stabbed into the small of Tenshu's back, exploiting an unarmored spot. Tenshu snarled in pain, his tail retracting to smack Taro away with enough force to send the puppet skidding across the ground.

Ren dove into the hole Misa had dug, vanishing from sight.

"Dammit," Tenshu muttered, his frustration mounting as another puppet, Daisuke, advanced. Daisuke swung his massive sword, the blade's flat striking Tenshu's side with a bone-rattling blow that sent him crashing through several trees, tearing apart the forest in his wake.

As Tenshu dug his claws into the ground to halt his momentum, another puppet, Seraphina, appeared before him. Her helmet opened, releasing a pink mist directly into Tenshu's face. His scales reacted instantly, shifting to form an airtight seal over his head, blocking the poison.

Tenshu roared, his fist pulling back before slamming into Seraphina's face, The punch connected with Seraphina's head, shattering her helmet and obliterating her skull in a gruesome spray of blood and fragments. Crimson splattered the ground, painting the battlefield with a macabre stroke of violence.

Without hesitation, he followed up with a second devastating blow to her midsection. The impact sent what remained of her upper body hurtling skyward like a broken marionette, trailing a sickening arc of blood in its wake.

Seraphina's mangled body halted mid-air, her legs the only part still intact. Slowly, regenerated her upper half. Tendrils of muscle and sinew stretched out like vines, binding together in a morbid reconstruction of flesh and bone. Skin crawled over the exposed tissue, knitting itself with unnatural precision until her body was whole once more.

As the regeneration was completed, her face was left exposed, and Tenshu froze.

"Ayame?!" he gasped, his voice breaking with a mix of disbelief and anguish. His eyes widened as he took in the familiar features.

-Ren Persouit-

Sasori sent a pulse of chakra through Ren's puppet body, his vision seamlessly transferring to the puppet's perspective. Through Ren's eyes, Sasori observed the crumbling tunnel ahead.

Ren flew into the hole, determined to pursue Misa, but the ground began to quake. The tunnel collapsed in a thunderous cascade of dirt and debris, burying Ren under the rubble.

Misa leaped out of the tunnel and into the cabin, her claws coated in dust as she scanned her surroundings. Spotting the child cowering in the corner, she smirked.

"There you are," she said, striding toward him. She reached down and grabbed the trembling boy. "Let's get you out of here—"

Her words were cut off by an explosion of lightning. The ground erupted in a blinding flash, debris raining down as a figure emerged from the chaos.

"What the—?!" Misa exclaimed, shielding her eyes.

Ren hovered above the small crater, his dual blades crackling with arcs of electricity. His glowing eyes locked onto her as he surged forward, a streak of lightning in the darkened cabin.

Ren lunged, slashing at Misa with relentless speed. She raised a clawed hand, deflecting both of his blades in a shower of sparks. Her other hand clutched the child tightly, her grip unrelenting.

"Dammit!" she snarled, her frustration boiling over. "Can't you just fuck off?!"

She swung her claws in a desperate counterattack, but Ren sidestepped with eerie precision, his lightning-coated blade slicing cleanly through her hand.

Misa let out a furious cry as her severed hand hit the ground. Blood spattered across the floor as she instinctively tightened her grip on the child with her remaining hand.

"Damn you!" she hissed, leaping toward the hole Sasori had created earlier. Without hesitation, she bolted into the forest, her feet barely touching the ground as she darted between the trees.

Ren gave chase, his twin blades crackling with energy, casting brief flashes of lightning through the dense forest. Trees blurred past as he closed the gap, his relentless focus honed on Misa's fleeing figure.

-With the Wives-

Makio sat impatiently in a chair, her arms crossed and her expression sour. The four of them gathered in the living room, each reacting differently to the tension. Hinatsuru glanced toward the window, her worry evident, while Suma busied herself dressing up Goro, who stood motionless as her unwilling mannequin.

"Hmm... brown hat or black?" Suma murmured, holding two tiny cowboy hats in her hands.

"Ugh! Where the hell is that bastard?!" Makio snapped, glaring at the puppet as though expecting a reply.

"Relax, Makio," Hinatsuru said, though her voice lacked conviction. "Sasori knows what he's doing."

"Yeah, yeah! Lord Tengen said he's dependable, so he must be!" Suma chimed in cheerfully, finally choosing the brown hat with a belt strip around the brim. She placed it on Goro's head with satisfaction.

Makio huffed, unconvinced. "Sure, but still—"

Before she could finish, Goro's body suddenly went limp, collapsing into Suma's arms.

"Ahhh!" Suma yelped, startled. "I—I don't think this is a good sign..." She held the lifeless puppet, her cheerfulness replaced by growing unease.

-Sasori VS Tenshu-

Tenshu's gaze burned with fury as he stared at the puppet once known as Ayame. "What the hell did you do to her?!" he demanded.

Ayame had once been a formidable demon whose ability to manipulate others' wills made her a nightmare for humans. Only those with overwhelming determination could resist her power.

Sasori smirked, his tone dripping with confidence. "Her power was far too useful to simply discard. Instead, I gave her a new purpose—a better existence than whatever miserable one she had before."

Tenshu's hands clenched into fists, his voice low and dangerous. "You're really pissing me off, Slayer."

Without warning, three of Tenshu's fingers dislocated, pointing toward Shiro, Daisuke, and Taro.

In an instant, scales launched from his fingertips at alarming speed. The first projectile struck Shiro's puppet body, obliterating it completely.

Sasori reacted swiftly, maneuvering Daisuke and Taro out of the line of fire. Even so, Daisuke lost an arm, and Taro's head was blown off.

While such damage didn't faze Sasori, it was enough to irritate him. He chuckled darkly. "You can weaponize your scales as projectiles? Interesting." There was a hint of excitement in his voice.

Tenshu gritted his teeth, glaring at Sasori.

"Seems I'll have to take you more seriously," Sasori said, his tone calm but menacing.

He dropped his connection to Goro, fully dedicating his focus to the battle. Swiftly, he performed a series of one-handed hand signs, raising his palm to the sky. A small tornado began forming in his hand, spiraling outward as it grew larger with each passing second.

Tenshu's eyes widened. 'This psycho can control puppets and wind?! What kind of Slayer is he?!'

Sasori's puppets ascended high into the sky, circling above as the tornado expanded. The winds howled, creating a deafening roar that rattled the trees.

"Let's see if your scales can withstand this!" Sasori declared. With a snap of his fingers, the tornado shattered, sending countless wind slashes spiraling in all directions.

Tenshu reacted instantly, moving his scales into a protective shield in front of him. One of the wind slashes collided with the shield, forcing him back. His feet dug into the ground, leaving deep trenches as he absorbed the brunt of the attack.

The scales shimmered under the moonlight, battered but unyielding. Tenshu lowered his shield, his scales retreating to cover his body once more. His eyes widened as he took in the devastation around him—the forest lay in ruins, miles of trees severed cleanly by Sasori's devastating wind attack.

"All this for one attack?" Tenshu muttered, disbelief etched across his face.

-Ren VS Misa-

Misa ran with desperate speed, clutching the child tightly. Her goal wasn't just survival; it was the child's safety. Whatever this Slayer had planned, she refused to find out.

Suddenly, a rogue wind slash tore through the forest, decapitating her. Her body stumbled, her perspective shifting as she watched trees crash to the ground from her disembodied viewpoint.

Ren seized the opportunity, his blade flashing as he severed her legs. Misa collapsed, her lower body disintegrating into ash.

Before her regeneration could fully kick in, Misa hurled the child into the air. Her headless body began knitting itself together midair. She hit the ground and burrowed quickly, creating a tunnel beneath the child's trajectory.

Ren dropped one of his blades and leapt, catching the falling child just before they hit the tunnel's opening. Looking down, he saw Misa waiting at the bottom, her claws outstretched and ready to reclaim the child.

Her eyes burned with fury as she clawed her way upward with terrifying speed. "Give him back!" she screeched, her voice a mix of rage and desperation. She swiped at Ren, but he deftly sidestepped the attack, retreating a few paces with the child still in his arms.

"Put the kid down!" she roared, glaring up at him. "You want me, right?! Come on, you bastard—fight me!"

The child wailed in Ren's arms, reaching a trembling hand toward the mole demon. Ren didn't respond. Instead, he carefully set the child behind a fallen tree, ensuring they were shielded from harm. Then, with deliberate precision, he retrieved his dropped sword.

Electricity danced along the edges of his twin blades, crackling with an ominous energy.

Misa's claws extended further, now resembling massive drills. Her size began to increase, her form twisting into something even more monstrous.

"I'm going to shred you into kindling, you useless plank!" she screamed, her voice devolving into a guttural roar.

-With the Wives-

"Did you hear that?" Suma asked nervously, placing the limp puppet Goro on the floor.

"Sounded like trees falling," Makio said, her brows furrowing.

"A lot of trees," Hinatsuru added, her voice uneasy as she bolted out of the house. She stopped in her tracks, her eyes widening in shock at the scene before her. Beyond a few layers of standing trees lay row upon row of thick trunks, cleanly severed, their splinters glittering in the faint light.

Hinatsuru ventured closer, stepping behind the unbroken tree line. Her breath caught as she gazed upon the forest's devastation, miles of felled timber spreading out like a lifeless plain. Her eyes darted toward the sounds of battle.

She saw Sasori engaged in combat with a massive, dragon-like demon, its thick scales shimmering as Sasori's puppets circled and attacked from the air. Off to the side, another battle raged—a mole-like demon clashed ferociously with a humanoid figure.

"MAKIO! NO!" Suma's voice shattered her focus, pulling her attention back to the house.

"Suma! What's wrong?!" Hinatsuru shouted as she rushed back inside.

"It's Makio! She went down the hole!" Suma cried, crouched near the opening in the floor where the refrigerator used to be. Tears streamed down her face as she gestured frantically.

"Damn it!" Hinatsuru cursed, her resolve hardening. Without hesitation, she jumped into the tunnel after Makio.

"Wait! Don't leave me alone!" Suma wailed, following them both despite her fear.

-Makio-

Makio sprinted through the winding tunnel, ignoring the faint echoes of Hinatsuru and Suma chasing after her. She wasn't about to wait—she needed to know what lay ahead.

Emerging from the tunnel, she found herself standing in what seemed to be the remains of a cabin, its structure split in two by some immense force.

"What the hell...?" Makio muttered, scanning her surroundings. Her eyes landed on Sasori, locked in battle with the dragon-like demon. His focus was absolute, his puppets darting and striking with precision.

She turned her head toward the other fight, where the mole demon and the puppet were locked in a deadly exchange. Her gaze shifted to something else—a crying child, sitting defenseless amid the chaos.

"A child?" Makio whispered. Her heart sank.

Without hesitation, she climbed out of the hole and dashed toward the child. "A kid shouldn't be anywhere near this!" she thought, scooping the trembling child into her arms. "Shh, it's okay. I've got you," Makio whispered, trying to soothe the crying child.

"Get your hands off him!" The mole demon roared, slapping the puppet away and lunging toward Makio. Its claws twisted together, forming a massive, drill-like appendage aimed directly at her.

Makio shielded the child with her body, bracing for the attack. But the strike never came.

She turned and saw one of Sasori's puppets, its claws blocking the blow. A bladed chain wrapped around the mole demon's claw, stopping the spinning drill mid-air.

"LET GO OF HIM, YOU BITCH!" the demon screeched, its voice filled with rage.

Before it could pull back, the puppet struck again—Ren's blade pierced through the demon's back, electricity surging into its body. Misa howled in agony, convulsing as the lightning coursed through her.

Sasori's puppet, Riku, tightened its bladed chain around her neck, severing her head in one fluid motion. The demon's head hit the ground with a thud before disintegrating into ash.

Makio clutched the child tightly, turning his face away from the sight of the demon's decaying body. The child's cries grew louder as Makio whispered, "Shh... it's over. You're safe now."

She looked down, her frown deepening as she noticed the mole demon's face contorted in despair. Its gaze lingered on the child as it dissolved into dust.

For a brief moment, Makio thought she saw something else in the demon's eyes—regret, maybe even love.

The wind carried away the last remnants of the demon's form, leaving only silence and the child's muffled sobs.

Makio stood, cradling the child in her arms. "Let's get you out of here," she murmured, her voice steady but her heart heavy with the weight of what she'd just witnessed.

-Sasori VS Tenshu-

'Damn it! I told them to stay back,' Sasori thought, irritation flaring as he maneuvered his puppets. Tenshu's thick armor repelled their strikes effortlessly, his massive frame absorbing even coordinated assaults.

Sasori's crimson eyes darted over the battlefield as he recalibrated his strategy. His puppets danced around Tenshu, seeking an opening to exploit. No luck. Suddenly, an idea sparked in his mind.

Reactivating Goro, Sasori sent the puppet into action. Its limbs twitched as it sprang to life, propelling itself through the broken window and ascending high into the air. Floating above the battlefield, Goro took aim at Tenshu.

From his sleeve, Sasori produced an explosive tag. He had only a few left—a rare resource he loathed to expend—but necessity left no room for hesitation. With deft precision, he tossed the tag into the air, simultaneously infusing it with chakra to increase its durability.

'Timing is everything,' Sasori mused as Goro fired.

The bullet struck the explosive tag mid-air, embedding the charged projectile directly into Tenshu's shoulder. A deafening boom followed, the explosion tearing through Tenshu's thick scales. His shoulder was left a scorched ruin, neck blackened, and half of his monstrous face disfigured by the blast.

Kenji, stationed strategically on the sidelines, sprang into action. His rapier gleamed as he darted forward, piercing Tenshu's neck with surgical precision.

The blade slipped through layers of muscle and sinew, reaching the demon's brain. Sasori's poison—meticulously crafted and stored within Kenji's weapon—coursed into Tenshu's system.

Tenshu roared in agony, his voice a guttural mix of rage and pain. In a blind swing, the demon's massive fist collided with Kenji, shattering the puppet into splinters. The rapier remained embedded in Tenshu's neck as he slumped slightly, pulling the broken blade free and tossing it aside.

A compartment in Sasori's arm opened with a mechanical whir, revealing a nozzle. Without hesitation, he unleashed a high-pressure stream of water aimed directly at Tenshu's chest.

The blast hit with incredible force, but Tenshu dug his claws into the ground, anchoring himself against the relentless attack.

"You piece of shit!" Tenshu snarled, his voice guttural and strained. His horns glowed faintly before he lunged his horn off his head, aiming his massive, scale-covered appendages at Sasori.

Sasori sidestepped the attack gracefully, chakra strings latching onto the lunging horn. With a fluid motion, he twisted his body, redirecting the charge.

The horn veered off course, slamming back into Tenshu's leg with devastating impact. The limb exploded in a spray of blood and shattered bone, leaving Tenshu crumpled and roaring in pain.

Sasori stood still, the faint hum of his chakra strings dissipating into silence. Tenshu's disfigured form lay sprawled across the battlefield, his strength fading.

"You never stood a chance," Sasori murmured coldly, his voice barely above a whisper. Around him, his puppets reassembled like shadows drawn irresistibly to their master.

Tenshu's breaths came in ragged, uneven gasps, each exhale rattling against the poison eating away at him. His scaled body convulsed, the once-imposing figure now reduced to a trembling, slumped heap. Defiance flickered in his eyes, but it was muted by an undercurrent of dawning horror.

"What... did you d-do to me, you p-piece of shit?" Tenshu snarled. The venom in his voice was diluted by his weakening state, each word a monumental effort.

Sasori stepped closer, his expression inscrutable save for the faint smirk tugging at his lips. "You're far too powerful to simply let die," he said, his tone calm and calculating. "Strength like yours... deserves more permanence."

Tenshu's clawed hand twitched, but his body betrayed him, collapsing forward into the dirt with a dull thud.

Sasori's smirk widened, his crimson gaze alight with triumph. "You'll join my eternal collection."

With a subtle flick of his fingers, chakra strings sprang to life, weaving through Tenshu's battered form. The ethereal threads coiled around the demon, binding his lifeless body like a marionette awaiting its first dance. Tenshu's remaining consciousness flickered weakly, just enough to register the invasive sensation of his limbs no longer being his own.

"This... isn't over," Tenshu rasped, his voice now a faint whisper, tinged with desperation.

Sasori knelt beside the fallen demon, his smirk hardening into something more sinister. His tone carried a chilling finality as he replied, "Oh, it's over." His fingers twitched, and Tenshu's limbs jerked involuntarily. "But for you, the real work is just beginning."

Tenshu's body gave one final, feeble spasm before going utterly limp. The poison had claimed the last vestiges of his resistance.

Sasori stood, his chakra strings pulling taut. Slowly, methodically, Tenshu's massive frame rose from the ground, now nothing more than a lifeless puppet under Sasori's absolute control. The battlefield fell silent, save for the faint creak of Tenshu's movements as Sasori manipulated his new creation.

He inspected his work, a glimmer of satisfaction in his eyes. "Perfect," he murmured, running his hand along the scorched and battered scales that now obeyed his every whim.

Sasori's cold gaze never left his new puppet as he took a step back, his fingers still manipulating the chakra strings. The giant, mutilated form of Tenshu—now twisted into a soulless marionette—stood before him, its once-fierce presence subdued into lifeless obedience.

"I'll name you... Ryukan," Sasori murmured, his voice low and final. The name resonated in the air, a symbol of his complete control over the beast.

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