The Demon Slayer Universe.
Mount Natagumo.
A pale silhouette fled in blind panic through the dark forest, desperate to escape an unspeakable monster.
“Why the hell does a monster like that even exist?!!!”
She was the “elder sister” of the spider family residing on this mountain; just minutes prior, an apocalyptic terror had ambushed their household without warning.
It had butchered and devoured her father, mother, elder brother, and younger siblings in cold blood.
Devouring them while shouting deranged battle cries:
“Mmm~~ Demon blood really is the ultimate protein shake!
Immortality!
Eternal youth!
Stand power!
Ripple breathing!!
HELL YEAH!!!”
Just recalling those words sent waves of paralyzing terror through her soul as she sprinted for her life.
“I have to run!
How could anyone possibly defeat a demon that feasts on demons?!!
Sorry, Rui, but this family roleplay is over—I want to live…
wait, what?!”
Glancing down, she realized a jagged bone whip had already impaled her torso straight from behind.
“H-How…
could this…”
A colossal kinetic pull reeled her backward, feeding her body into the monster’s yawning gullet in the blink of an eye.
“You’re next on the menu, Lower Moon Five, Rui.”
The fanged abomination coated in ravenous mouths was none other than Horne in his [Army into One] state, his crimson gaze locking onto the pale young boy nearby.
Etched into the boy’s left iris was the kanji for Lower Five.
One of the Twelve Kizuki serving directly under the Demon King Muzan: Lower Rank Five, Rui.
Entrenched on Mount Natagumo, he ran a counterfeit family, occasionally descending to devour villagers or slaughtering hikers who wandered into his webs.
A pathetic family-obsessed psycho.
“Hmph.
Where did a filthy stray demon like you crawl out from, daring to cause havoc on my turf?!
How dare you butcher my family!
Damn you!
Do you have any idea how exhausting it is to assemble family members that meet my standards?!!
Now that those useless worms are slaughtered, I have to start all over again!!
But before that, I’ll teach you the absolute gulf in power between the Twelve Kizuki and an insect like you!!”
Rui merely flicked a finger, sending an imperceptible razor thread slicing through the bone blade on Horne’s right forearm.
“Slicing attacks executed with micro-threads—ensuring absolute stealth while maintaining razor lethality.
You managed to snap my bone blade, so I’ll give you credit for that.
But that’s where your luck runs out.”
Horne took slow, heavy steps toward Rui.
“Arrogant garbage!”
Rui splayed his ten fingers, his digits dancing like a puppeteer to unleash a torrential storm of invisible cutting threads.
The slashes closed in from every conceivable angle, forming an inescapable net of slaughter.
A deluge of thread blades slammed into Horne’s frame, cleaving off every protruding bone blade and spur.
Yet that was all.
The core shell of [Army into One] didn’t suffer a single scratch.
“HAHAHA!
HINJAKU!
HINJAKU!
How could such pathetic, limp-dicked attacks ever breach the iron defense of [Army into One]?!!”
Invisible razor threads sounded terrifying on paper, but in reality, they lacked raw kinetic mass.
Without sufficient mass, there was no kinetic punch.
If a fast-moving object slammed headlong into a taut wire, it would easily be sliced apart.
However, whipping a flimsy wire against an immovable, ultra-dense barrier was an exercise in futility.
Without raw pressure behind the edge, even monomolecular sharpness couldn’t cut through absolute defense.
“Tch!
Don’t get cocky!
You’re just hiding inside a turtle shell!!”
Realizing direct slashing was ineffective, Rui shifted tactics.
His crimson threads coiled tightly around Horne’s limbs and torso, constricting violently to garrote his armored body into chunks.
A cute plan, but Rui never stopped to wonder why Horne remained so calm.
Jagged bone blades erupted from Horne’s forearms once more, but this time, they were fundamentally different.
The blades pulsed with shimmering, blinding light, slicing Rui’s steel-hard threads apart like wet paper.
“Impossible!
My threads are stronger than steel—how could they be severed so effortlessly?!!”
Rui knew the insane tensile strength of his demonic threads, leaving him completely flabbergasted.
“What the hell is that glowing blade?!”
With his limited perspective, he couldn’t comprehend how a simple layer of refracted light could grant such absurd cutting power.
But Horne knew.
This was the Mode of Light—the signature combat technique pioneered by Kars the Pillar Man.
Chainsaw-like serrations rotated along the edge at ultrasonic speed, granting peerless shredding capacity.
As the microscopic teeth spun, they refracted light into a radiant sheen, making the bone blade appear to glow like a lightsaber.
And now, Horne went on the offensive.
“Heh~ Had your fun playing cat’s cradle, you little brat?”
In the blink of an eye, Horne flashed behind Rui, lopping off both of the demon’s arms and feeding them to his armor.
“Mmm~ Twelve Kizuki blood really hits the spot!
Fucking delicious!!”
The speed was so blinding that Rui didn’t even register the strike until Horne was already talking shit behind him.
“T-This…
how is this possible?!
Who the hell are you?!!”
Terror-stricken, Rui tried desperately to leap away from this unfathomable apex predator.
Yet the moment he exerted force through his legs, clean crimson seams split across his thighs—both legs dropped off cleanly, sending him crashing onto the dirt.
“When did you even slice them?!!”
Before he could even attempt to reattach his severed limbs, two barbed whips snared the legs and yanked them into the armor’s maws.
Left with no choice, Rui burned blood to regenerate his limbs at emergency speed.
Horne gave him zero breathing room: a muscular, barbed whip surged from the colossal maw on his chest, dragging Rui directly into the gaping abyss to be ground into fertilizer.
The secret behind Horne’s explosive leap in power was the Ripple enhancements boosting his JoJo vessel—stacking the stats across both bodies elevated his combat rating directly into the Upper Moon tier.
With the entire spider family reuniting peacefully inside Horne’s stomach…
Shinobu, who had been observing from the shadows, stepped out beside him.
“Horne, have your injuries fully recovered?”
She recalled his charred, blackened body earlier, completely reliant on the Stand armor just to force his broken bones to move.
He could have easily relied on Shinobu to hunt weak demons to replenish his blood and mend his flesh.
Yet this stubborn, iron-willed warrior insisted on hunting Lower Moon Five in that crippled state with pure grit.
Beyond her profound respect, Shinobu couldn’t stop her heart from aching for him.
“Good as new!
See for yourself!”
With a thought, Horne dismissed [Army into One], revealing his chiseled face and towering, hyper-muscular physique in all its flawless glory.
And, of course, that miraculous biological staff swinging proudly between his legs.
Shinobu flushed crimson once more, but the initial disgust was long gone, replaced by a racing pulse and intoxicating heat in her chest.
“Nothing beats Twelve Kizuki blood.
Eating Lower Five healed every scrap of internal damage and left me with huge blood reserves to spare.
You can only imagine how many thousands of innocent humans these monsters devoured to accumulate this much juice.”
In devouring Rui, Horne had effectively exacted vengeance for every single victim.
“What’s our next move?”
Shinobu asked softly, having already decided to follow him wherever he went.
“To the Butterfly Mansion.
I need to synthesize a method to permanently purge the cannibalistic urge.
The grand hunt for the Twelve Kizuki begins after that—and I have a feeling your Master’s crow is already on its way.”
Just as Horne predicted, deep within the Demon Slayer Corps headquarters at the Ubuyashiki estate…
The Master of the Corps was listening intently as his wife read aloud the urgent supplementary report sent by Shinobu Kocho.
His eyesight was nearly extinguished by the familial curse rotting his face.
“Not only the secrets of the Bright Red Nichirin Blades, but an entirely unknown Breathing Technique…
This demon named Horne grows more fascinating by the hour.”
As a divine hereditary gift of the Ubuyashiki lineage, they possessed flashes of prophetic foresight.
Yet across every possible future he had glimpsed, he had never once foreseen the emergence of an anomaly like this.
Nevertheless, his infallible intuition told him that the long-awaited day of Muzan Kibutsuji’s downfall was rushing toward them at breakneck speed.
To that end, he had to make every conceivable preparation.