Deep within Infinity Castle, Kibutsuji Muzan stood with his back to the only entrance that could be called a door, like a cold tombstone.
He wore a meticulously tailored black suit, making his skin appear even paler, and his overall appearance vaguely carried the stage style of a certain pop king.
His gaze was fixed on an ancient painting hanging on the wall.
In the painting, Blue Spider Lilies bloomed, a counterfeit drawn from fragmented records and imagination—a physical manifestation of his thousand-year obsession.
It was the only obsession that carried him through a millennium of darkness, the embodiment of the hunger gnawing at the deepest part of his soul.
In the silence, only the faint sound of his own blood flowing through his veins could be heard.
No, perhaps also the suppressed breaths and heartbeats of the demons he kept or who had willingly joined him in the depths of Infinity Castle—background noise, automatically filtered by his keen senses.
Suddenly, under the skin of his left temple, a few tiny blood vessels wriggled unnaturally, as if invisible threads were pulling beneath the skin, or as if minuscule parasites were burrowing.
This strange sensation instantly broke his gaze into the illusory other shore.
His face, usually as expressionless as a refined mask, twisted in an instant.
His gums clenched tightly, producing a tooth-grinding friction sound, while veins bulged on his forehead like twisted earthworms.
Through the connection forged by a venomous curse deep within his bloodline, a familiar point of light was extinguished.
Lower Moon One, Yan Meng.
“Worthless.”
A cold word squeezed out from Muzan’s clenched teeth, carrying undisguised anger.
He closed his eyes, focusing his mind, forcibly capturing the last trace of connection through the bloodline, reading the information Yan Meng sent back before death.
Fragmented, broken images crashed into his consciousness.
A noisy, crowded space filled with the heavy scent of humans and cheap tobacco.
It was a train station platform.
Yan Meng snapped his fingers triumphantly, and passengers around him collapsed into unconsciousness. The sickly joy he felt seemed to travel through the bloodline.
Then, the scene spun violently.
Amid chaotic lights and shadows, an unusually tall figure in a dark monk’s robe crashed into view like a tower.
The strange weapon in his hand, attached to heavy chains, came crashing down with a howl that tore the air.
The scene shook violently, accompanied by the sickening sound of bones shattering and an explosion of shock and agony from deep within Yan Meng’s consciousness.
“Hashira? Why would there be a Hashira in a place like this?”
Next came a suffocating chase.
The viewpoint was low, panicked.
Yan Meng tried to raise his left hand, infused with Blood Demon Art, to unleash his signature hypnotic sound, but it was grazed by the incoming meteor hammer.
The intense pain of his entire left arm turning to dust transmitted clearly—even Muzan could almost feel the nerves being crushed.
Yan Meng staggered back, hiding desperately behind the bodies of sleeping humans, like a startled insect seeking a gap.
He futilely lifted his remaining right hand, desperately pointing at his own eyes.
The bizarre hypnotic patterns in his pupils, painstakingly constructed for forced hypnosis, spun wildly.
“Look into my eyes! Sleep—”
Yet, the towering figure’s forward movement didn’t pause for a moment.
Muzan “saw” it clearly, through Yan Meng’s despairing vision—the eyes were completely unfocused, gray-white and hollow.
A blind man.
The visual hypnosis Yan Meng relied on, his greatest pride, was utterly useless against someone who had lost their sight.
Despair, like icy water, instantly drowned the last of Yan Meng’s consciousness.
The next scenes made Muzan feel the same irritation as being offended by a lowly creature.
Yan Meng, like a frightened rat, fled chaotically among the sleeping crowd, his movements clumsy and laughable without the aid of Blood Demon Art.
To Muzan, the Stone Hashira’s attacks weren’t particularly fast, nor overwhelmingly strong, but each strike hit Yan Meng.
Yan Meng’s severed left arm tried to regenerate over and over—just as a small bit of flesh began to grow, it was smashed again by the pursuing meteor hammer or the broad axe, with the regeneration speed visibly slowing. The wounds around him were a mess, purplish-black and festering.
Finally, the view expanded to infinity—a metal hammer head roaring with the wind of death, and darkness that swallowed even consciousness.
The flow of information stopped abruptly, as if a film strip had been cut.
Muzan’s eyes snapped open, scarlet pupils boiling with violent rage, nearly bursting forth as blood-red light.
The Lower Moon he had carefully selected and bestowed with precious blood died so pathetically!
In a filthy corner filled with lowly humans, taken down by a Hashira whose abilities clearly countered his own, and whose fighting style was almost clumsy and crude—eliminated in a manner akin to mockery!
This wasn’t just Yan Meng’s personal incompetence—it was an insult to Kibutsuji Muzan’s own judgment!
A denial of the value of his creations!
“Worthless! Completely worthless!”
Muzan roared, his voice echoing in the empty room, filled with uncontrollable fury.
His pale fingers clenched suddenly, nails nearly piercing his palm.
He recalled the fighting style in the vision—pure reliance on hearing and touch, wide and forceful moves, powerful, but not especially fast or agile.
If it had been another Lower Moon adept at speed or direct combat-type Blood Demon Art, perhaps the outcome would’ve been different.
But it had to be Yan Meng, a being reliant on mental control and physically fragile, who charged in and performed so poorly that he couldn’t even delay the opponent or relay more effective information before dying.
“Unable to overcome even such minor disadvantages, unable to inflict serious injury on the enemy before dying—utterly wasting the blood I bestowed!”
Rage crashed through his inhuman chest, making him want to immediately crush the remaining Lower Moon demons through the bloodline connection, using their screams to vent his dissatisfaction.
Raising this lot was a waste of precious blood, aside from the occasional use for clearing out riffraff.
For centuries, the Upper Moon ranks had only shifted internally, the core members remaining stable.
And the records of Hashira deaths in the Demon Slayer Corps were almost all caused by the Upper Moon.
Lower Moon?
Hmph, nothing but a pile of useless mud, consumables, defective goods to be discarded at any time.
Perhaps, it was time for a complete purge.
“Looks like I’ve been too lenient with them lately.”
Muzan murmured softly.
His pale fingers unconsciously tapped the table beside him with his nails, producing a tense “tap, tap” sound.
In the dead silence of Infinity Castle, this sound echoed faintly, like a death knell in the hearts of every Lower Moon demon.
He had no need for trash. Absolute obedience was just the baseline—tools without value didn’t even deserve to exist.
Inferior products so easily dispatched by a Hashira—all had to be eliminated.
The power of the Upper Moon was already enough to crush the Demon Slayer Corps. Lower Moon, these defective products, should never have existed, only dragging down the status of demons…
But then, a peculiar image flashed through his mind.
Lower Fifth, Rui.
The little demon obsessed with twisted, false familial bonds, confining himself to a spider’s playhouse on Natagumo Mountain.
Muzan’s raging murderous intent faltered slightly.
Rui’s childhood—those years tormented by illness and shunned by family—bore too many unpleasant similarities to his own human past.
Every time he saw Rui, it brought up those dark memories from his weaker days he desperately wanted to forget.
This subtle connection granted him a trace of indescribable tolerance toward Rui—something Muzan himself was unwilling to admit.
For this reason, Rui was the only demon allowed to gather multiple others and form a so-called family—a unique exception.
Even though such behavior clearly diluted power and was useless for finding the Blue Spider Lily, Muzan never imposed the harsh punishments on him as he did on other unruly demons.
This was one of the few indulgences in his long life.
“Forget it.”
Muzan’s fingers stopped tapping the table.
He decided to give these failures one last chance.
A chance to prove they possessed even a sliver of utility.
As for Yan Meng…
Muzan snorted coldly, the last flicker of emotion in his eyes vanishing into icy indifference.
Although Yan Meng’s penchant for deriving pleasure from others’ pain and seeking extreme sensory stimulation somewhat matched his own aesthetic of evil—making him more tolerable than the weeping or hate-filled demons—
Being killed by a Hashira meant that was all there was to him.
A worthless creature unable to properly wield his own powers, easily destroyed by a countered opponent—dead was dead.
He could only blame his own incompetence, unworthy of the blood and immortality Kibutsuji Muzan bestowed.
Muzan had no desire to waste further emotion on such a loser.
But the Demon Slayer Corps—especially that blind Hashira—
He had taken note of this debt.
When he found the true Blue Spider Lily, completed his ultimate evolution, and transcended all life to become a perfect, eternal being—
He would personally crush these bothersome insects of the Demon Slayer Corps, Hashira and all, into flesh and mud, forcing them to repent in endless pain and despair for daring to oppose his greatness!
“Mingnu.”
Muzan issued an order into the empty room, his voice returning to its usual coldness.
The only reply was a faint, monotone sound of a biwa string, echoing from nowhere.
As the string’s note resonated, the space around the room rippled subtly, as if invisible waves spread outward, causing the entire structure of Infinity Castle to undergo faint, imperceptible shifts.
“Transmit orders to all Lower Moon.”
Muzan’s voice was devoid of emotion, like a death sentence carved into cold stone.
“Upon encountering members of the Demon Slayer Corps—especially Hashira—kill them all with full force. Leave none alive.
If any more Lower Moon end up like Yan Meng—useless and lost—there’s no reason for their existence. I have no use for trash that can’t even clean up humans.”
“Zheng –“
The biwa sounded again, as if in response.
Through Mingnu’s Blood Demon Art, this command was silently transmitted to every Lower Moon demon’s location.
Muzan said nothing more, his gaze returning to the fake painting of the Blue Spider Lily on the wall.
The violence and murderous intent in his eyes gradually gave way to a deeper longing.
It was greed for eternal life under the sun—the sole obsession that carried him through a thousand years of darkness and endless loneliness.
By comparison, the fate of the Lower Moon, or even the provocations of the Demon Slayer Corps, were mere dust on the path to his ultimate goal.
***
On another branch of the same timeline, the machinery of the Demon Slayer Corps, dormant for so long, began to turn quietly faster—thanks to the butterfly named Shi Hanfeng who had wandered in by chance.
With the clues he provided, the Hidden Division under the Ubuyashiki Clan and the scouts in charge of the perimeter quickly began targeted investigations.
The efficiency was surprisingly high.
Soon, the main suspect area was locked in.
A mountain in a remote region, perpetually shrouded in damp, cold mist and ominous atmosphere.
Steep terrain, thickly wooded and gloomy, where villagers frequently vanished while collecting herbs or chopping wood—enough to raise suspicions of unknown demon threats in these times of rampant evil.
But what truly confirmed this as Natagumo Mountain to the Demon Slayer Corps investigators were the horrifying rumors spreading in the villages below.
Villagers whispered about giant spider monsters living in the mountain, using white threads to capture humans and drag prey away cocooned.
But when pressed for details, no one could describe the spider monster’s appearance clearly—the forms were strange and varied.
The reason these terrifying tales spread yet remained shrouded in vagueness, like fog, was simple.
Those who had seen the true face of the spider monster up close, or strayed deep into the forest’s forbidden zones, almost never returned alive.
The few survivors, gripped by terror, only glimpsed enormous webs hanging in the forest or caught fleeting, shadowy forms in the mist.
Such fragmented horrors, transmitted by word of mouth and imagination, became bizarre legends that kept ordinary people away.
The messenger crow confirming the news soared through the heavy night sky, delivering a coded, brief message into Shi Hanfeng’s hand as he loitered outside a tavern in a certain town.
“Natagumo Mountain… Lower Fifth…”
Shi Hanfeng unrolled the small slip of paper at his fingertips, his gaze passing over the concise location.
He rubbed his chin thoughtfully.
The Lower Fifth obsessed with twisted family bonds, trapping himself in a game of false family—a unique existence even among demons.
Or rather, the method of building a family and distributing abilities was itself intriguing.
Rui could use tough threads for attack and restraint, while the Blood Demon Art granted to his family members varied wildly—physical enhancement, venom that turned humans into spiders, thread manipulation…
This setup was reminiscent of a weaker version of Muzan’s bloodline control.
If he were killed, what would drop?
Shi Hanfeng pondered instinctively.
This type of ability, focused on precise control, endowment, and connection, didn’t match any Zanpakuto in his memory.
Shinigami power systems were more about direct elemental explosions, rule manipulation, concept embodiment, or simple physical energy enhancement.
Such fine manipulation of threads and puppeteering really didn’t fit the style.
But his thoughts quickly broke out of that frame.
Why be limited to the realm of Shinigami?
Qianbian’s core was understanding and reconstruction—in theory, as long as the rules or concepts contained in the material were clear enough, the directions for transformation should be limitless.
Excluding the Shinigami system, he immediately thought of another existence.
Not famed for threads, but whose core ability involved “connection,” “dominion,” and “collective” concepts…
Of course, the details might not be identical, but the idea of connecting others with invisible bonds, constructing a false community, and drawing power or twisted satisfaction from it was strikingly similar.
If he could gain such an ability, it would be valuable for tactical deception, intelligence theft, or even large-scale chaos in the future.
Of course, he’d also need to be careful not to draw the wrath of a certain Earth god eating instant noodles on the moon.
“Perfect timing,”
Shi Hanfeng murmured, eyes shining with eager anticipation.
Like a child with a new toy, he couldn’t wait to test it out.
I just learned some grappling moves!
“Sleep comes, and someone brings a pillow. With new powers, if you don’t test their effects and limits in actual combat, how will you know the boundaries?”
The weakened Jinghua Shuiyue ability acquired after Qianbian’s Shikai.
Manipulating the five senses, creating illusions—this was a type that demanded extensive combat to familiarize, hone, and master.
And Rui and his Spider Family were undoubtedly the perfect whetstone.
To test the permeability of illusion abilities, their effects on different senses, and the limits of control over group targets—there was no better opportunity.
A script began forming in his mind: using Jinghua Shuiyue’s illusion powers to disguise himself as a Hashira, he would stage a fierce, evenly matched battle with Rui, ultimately killing him in a hard-won victory—suffering heavy injuries or even death in his disguised identity.
This would allow him to harvest materials, test new powers, and create false reports of Hashira-level casualties for the Demon Slayer Corps, further deceiving Muzan.
In any case, the rewards for Lower Moon kills were unlikely to be reaped fully, given Muzan’s capricious temperament.
The other Lower Moon in the original story didn’t even leave traces behind—finding them would be time-consuming and inefficient.
But by eliminating Rui, this unique Lower Moon, Muzan’s fury would almost certainly lead to the abolishment of the entire Lower Moon hierarchy.
Even Yan Meng, that pleasure-seeker, wasn’t spared in the original—whether he could survive a few years earlier was uncertain.
Getting a freebie was just a pleasant surprise.
With the ultimate goal of killing Muzan, there was only one Upper Moon he absolutely couldn’t let go—any others could be abandoned.
But now, with the gift from Yan Meng, the plan could be changed.
Now, it was time to deliver a grand gift to that problem child obsessed with twisted games of family.