Human adaptability can be terrifyingly resilient.
The next morning, the sunlight was almost painfully bright.
The restaurant was filled with the smell of fried eggs and toasted bread, mixed with the faint bitterness of coffee. Shinobu Kocho sat with the others at a long table for breakfast, wearing a Demon Slayer Corps outfit formed by the Word-Bound Tights, but styled in New Eridu's fashionable, modern aesthetic.
Occasionally, knives and forks tapped against porcelain with crisp little sounds.
For Shinobu, the first few minutes felt stretched and warped—each second longer than it should have been.
She kept her head lowered, sipping milk in small, careful mouthfuls, while her peripheral vision—sharp as ever—caught every glance that seemed to drift her way.
Every time she looked up, she felt as if everyone across from her, beside her, even the Bangboo in the distance, were staring with invisible needles—judging, carving words into her skin:
Shameless.
In her imagination, their thoughts were already sneering:
"So this righteous 'Insect Hashira' is walking around like this?"
"Just sitting there in public without a shred of embarrassment…?"
"The 'guardian of the Butterfly Estate'? She's just a shameless little girl."
The thoughts swirled and screamed in her mind until the food—however delicious—tasted like dry paper.
She forced the familiar gentle smile onto her lips, but the tightness beneath it was hard to hide. She could feel warmth climbing her cheeks, her heartbeat pounding in her chest, her ears slowly turning red. She lowered her lashes and focused on her plate as if it were the most important thing in the world.
And yet—within the span of a single breakfast—
Sakiko naturally slid a small dish of sauce toward her, her sky-blue hair catching the sunlight, her gaze clear and casual.
"Try this, Shinobu. It goes really well with the eggs."
Then came simple, ordinary questions—"How does it taste?" "Want more soup?"—spoken with the relaxed rhythm of everyday life.
Shinobu's tension loosened, little by little.
She lifted her eyes carefully, scanning faces around the table:
Tsunade was eating with gusto, laughing loudly while talking about last night's cards.
Kafka drank coffee with elegant restraint, her eyes gentle.
Mash ate quietly, offering a shy smile now and then.
Rin was animatedly reenacting a movie scene from the night before.
Sakiko stirred her cereal absentmindedly, looking half-lost in her own thoughts.
There was no mockery. No contempt. Not even the smallest trace of malice.
Shinobu suddenly understood—those "judging looks," those cruel inner voices, were nothing but her own over-sharpened imagination.
Not a single one of them treated her outfit as strange. If anything, they were almost too considerate of her.
That sense of being fully accepted—of being protected and fussed over—felt oddly unfamiliar to Shinobu, who was used to being the caretaker, the one who held everyone else together. But then again… among everyone present, she truly was the youngest.
The last remnants of awkwardness and shame evaporated under their calm normalcy.
By the time she finished eating, the discomfort tied to her clothing had disappeared. Her usual composure returned—quiet, steady, almost serene.
If even the people who knew the truth behind this outfit didn't look at her differently… then in the eyes of strangers who knew nothing, it was simply an unusual style of clothing. Nothing more.
Her smile regained its warmth.
She stood, turned to Eisen, and bowed lightly. Her movements were smooth now, no stiffness remaining. Her tone was as polite and gentle as ever, but there was an almost imperceptible relief beneath it.
"Then, Guildmaster… I'll return to my world and await your visit."
Eisen nodded, saying nothing unnecessary.
In the next instant, Shinobu's figure vanished—like a line of ink erased from paper.
One second later, Eisen himself disappeared as if he had dissolved into the air.
The moment they were gone, the restaurant's relaxed mood detonated into a completely different kind of energy.
The remaining five women all sprang up almost at once and clustered around a small round table, the air thick with unabashed gossip.
"Did you see it?!" Rin couldn't hold back. She pressed her hands together at her chest, leaning forward so hard she looked ready to bounce out of her shoes.
"When Shinobu first came out—her face was so red! Like a ripe apple! She was so embarrassed. She was adorable!"
Her eyes sparkled as if she'd uncovered a world-shaking secret.
Sakiko flicked her long blue hair and propped her chin on her hand, trying to look indifferent.
"What's so surprising about that? She's wearing clothing made from the Word-Bound Tights. At the end of the day, it's basically like walking around wrapped in a single piece of hosiery. Feeling embarrassed is the normal human response."
She paused, then added bluntly,
"If someone could wear it completely shamelessly without feeling anything, that would be scary."
As a high schooler, Sakiko's take was exactly what you'd expect—sensitive, painfully aware of appearances, fiercely protective of dignity.
Tsunade let out a derisive snort, arms crossed.
"Spoken like a kid who still goes to school—stuck on surface-level nonsense. When you live as long as I have, you learn: convenience wins. Practicality wins. That's all that matters."
"Who cares what other people think? And besides, those clothes look normal and even feel normal. What's there to agonize over? Your comfort comes first."
Kafka lifted her coffee with effortless grace, smiling as she nodded along.
"Exactly. And don't forget the extra benefit: your body stays perfectly clean—no dirt, no odor, no sweat problems. Sakiko…"
She tilted her head slightly, voice soft and precise.
"…are you really not tempted?"
Sakiko instantly choked. Her confident posture deflated like a punctured balloon.
Her lips parted. No sound came out. Color surged into her cheeks as her eyes darted away from Kafka.
Of course she was tempted.
What girl wouldn't be?
The thought of crowded places, important moments, the nightmare of someone catching a whiff of sweat—or noticing an embarrassing stain—was enough to make her want to melt into the floor.
"Permanent cleanliness" was an almost cruelly perfect temptation for a teenager.
But admitting it out loud felt mortifying.
Mash sat quietly with faint color on her cheeks.
Among them, her acceptance of the concept was ironically the highest.
Because in Mash's world—Fate's world—the "spiritron dresses" of Heroic Spirits were often… beyond explanation.
Whether from artistic intent or sheer mischief, many outfits pushed exposure and design choices to the edge of absurdity.
Even Mash herself—after becoming a Servant—had worn combat gear that could hardly be described as conservative.
And that was still on the milder end.
Her mind flashed with images of other Servants—friends, foes, legends—whose outfits were so bold that merely remembering them made her face heat up.
So the discussion about whether "a bodysuit-like garment" was shameful or not…
Mash couldn't bring herself to speak.
She certainly couldn't admit, in a room full of women who still looked "normally dressed," that she'd fought countless battles in skin-tight gear while facing enemies dressed far more provocatively.
So she stayed silent, cheeks warm.
Meanwhile—
Almost the instant Shinobu returned, Eisen—after receiving her consent—used group transfer to enter the world of Demon Slayer.
Because Shinobu hadn't brought anyone along in a subgroup last night, the time flow in her world had frozen at the moment she left.
So it was still the same silent night.
The forest air was cold, heavy with dew and the scent of grass. Far away, faint insects chirped, making the stillness feel even deeper.
The moment Eisen appeared beside her, his gaze first flicked to the ground not far away.
A puddle of viscous purple-black residue glistened under moonlight, giving off a faint, rotten stench.
Eisen understood immediately.
"That must be what she mentioned—the remains of the demon she just poisoned."
After confirming, he gave it no more attention.
He turned to Shinobu.
She still wore her gentle, mask-like smile, but under the moonlight he could clearly see the seriousness in her eyes—the expectancy she tried to hide.
"I'll begin analyzing your world."
His voice was clear in the night.
Shinobu's smile didn't move, but her gaze sharpened. She nodded once, firmly.
"Thank you, Guildmaster."
Eisen closed his eyes and released his perception.
At the same time, a powerful resistance wrapped around him in layered pressure, cutting his senses down drastically.
As he had expected, his perception was heavily restricted here.
In all the worlds he'd visited, this was the most severe limitation he'd ever encountered.
Even so, he forced his awareness into contact with the world's core information stream.
And the moment he received that vast flood of data, Eisen's mind jolted—not because he'd discovered some dramatic "secret," but because the texture of the information itself felt strangely familiar.
In the past, he had explained that what he perceived wasn't simple imagery—sound, smell, or sight—but a higher-dimensional bundle of pure "sense": it contained everything, yet couldn't be cleanly described as a single tree, a single birdcall.
Until now, he had considered this perception efficient but lacking the visceral impact of seeing with one's own eyes.
But in this instant, a thought struck him like lightning:
Isn't this exactly what large-model AI does—breaking reality down, encoding it into high-dimensional feature vectors?
Turning concrete reality into abstract coordinates… then understanding the world through the relationships between those coordinates.
So he had been operating in a way eerily similar to AI principles—without ever consciously framing it that way.
And in the multiverse, this perspective wasn't unique. Mash's world had "Alaya"—a phenomenon that, in a different language, seemed to rhyme with the same structure.
A new thought rose:
What happens if this kind of high-dimensional perception is combined with large-model AI techniques?
But the thought passed in an instant.
Right now, his priority was Shinobu's world.
In Shinobu's perception, Eisen had only closed his eyes for a brief moment before opening them again.
He withdrew his senses, his expression turning faintly odd, as if weighing his words.
Then he looked at Shinobu and spoke bluntly.
"I have good news and bad news. Which do you want first?"
Shinobu's smile remained unchanged. She didn't hesitate.
"The bad news."
Eisen nodded, unsurprised. His gaze hardened.
"I explained yesterday how my 'world rewind' works: I ignite First Flame at a high-dimensional layer and burn backward from the end of time, passing through the present until only the past remains."
Shinobu's eyes flickered. She'd already guessed what was coming.
Her heart clenched—but her smile didn't move. Only her fingers, hidden inside her sleeves, curled slightly.
Eisen continued.
"But this method has a limitation. It cannot cross a worldline's key node."
He met her eyes and spoke the cold conclusion clearly.
"And your current point in time is before that key node. Meaning: I cannot merely rewind your world to before your sister's death—I can't even initiate a rewind in this world at all."
He shook his head once.
"In other words, I cannot provide you with a safety net here. No do-overs. No margin for error. If you fail, there is no second attempt. That is the worst bad news."
Shinobu stood straight, her gentle smile perfectly intact.
Only someone standing extremely close might have noticed the slightest tremor in her lashes.
Maybe—deep in the locked lake of her heart—there was a ripple of disappointment, so small it could barely be called a feeling.
But it vanished instantly beneath the ice.
Because Shinobu had never truly pinned her hope on miracles like turning back time.
After a brief silence, she spoke calmly, as if Eisen had just told her something trivial.
"I see."
She nodded once, then lifted her eyes. Every emotion was sealed away neatly.
"Then, Guildmaster… under these restrictions, how much of your strength can you still use?"
Eisen's casualness disappeared. He frowned, sensing an invisible shackle.
"Very little," he admitted.
"Extremely little. If we're talking raw 'paper strength,' you might not even lose to me here."
He spread his hands with a helpless shrug.
"This world suppresses other systems too violently. Almost no 'supernatural substrate' can seep in."
Of course, dying was impossible; even being injured was difficult. But that wasn't the point.
In this world, only Muzan Kibutsuji—by virtue of how much "weight" he held in the world's narrative structure—might possess enough of the world's own authority to truly harm Eisen.
And aside from Muzan… perhaps only one person could do it through sheer talent.
After a pause, Eisen broke the stillness.
"Shinobu. Attack me once."
His eyes became focused.
"High-dimensional sensing gives me only a blurry understanding. I want something direct."
Then, with honest confusion, he added:
"I still don't understand how a world with no obvious supernatural foundation can produce 'demons' that violate reality this thoroughly. And how humans—mere humans—can reach the point where they not only harm them, but kill them permanently. Why does this work at all?"
Shinobu didn't hesitate. She nodded, becoming equally serious.
"Understood. Please observe closely."
Her fingers touched her sword—
And her body vanished from where she stood.
Whoosh—!
The air split a heartbeat later, sharp as a scream—like the buzz of a poisonous insect magnified to the edge of pain.
Her thin, specialized Nichirin blade—more stinger than sword—thrust toward Eisen's left ear with surgical precision, carrying a cold line of light.
The tip stopped just short, the wind lifting a few strands of his hair.
Bee Sting Dance: True Drag.
The air hissed faintly at the point of near-contact.
Fast. Accurate. Lethal—yet perfectly controlled. She did not harm him at all.
Eisen didn't move. Not an inch.
His eyes remained calm. He simply turned his head slightly, tracking the path of the blade, then fell into deep thought.
Moonlight carved a quiet profile along his face.
Shinobu rotated her wrist and sheathed her blade smoothly, the metal whispering against the scabbard—
Click.
The moment the guard met the mouth of the sheath and the sound finalized—
The world collapsed.
The forest, the moonlight, the night—shattered into fragments and vanished.
In their place: titanic continents cracked and broken, grinding together with deafening roars as they crushed inward.
The earth beneath was no longer soft soil, but dead, cold ground—filled with countless broken swords thrust into it, stretching to the horizon.
Each blade radiated despair, grit, and stubborn will.
The sky was no longer night. It was soaked in a suffocating blood-red dusk.
The sun was eclipsed—no, devoured—by a vast darkness, leaving only a thin burning ring at its edge.
Or rather… it was as if a hole had been torn through the sun itself.
From that hole poured black viscous matter like a filthy waterfall, endlessly spilling downward—drenching the figure who stood at the center of the swordfield.
And Eisen—
Eisen had become impossibly tall.
He wore a savage knight's armor that looked as if it had been re-forged in molten heat, seams glowing like lava.
A pressure more terrible than any killing intent erupted from him—an existential weight that crushed the soul.
Shinobu's pupils shrank to pinpoints.
Her body turned to stone. She couldn't even move a finger.
Her heart hammered as if it would explode. Terror wrapped her limbs like an icy serpent. Her thoughts cracked like glass.
This wasn't a mere "presence."
This was the terror of a gulf in being.
What is this?!
A divine punishment? The end of the world? Or—
A fragment of the Guildmaster's true self?
The vision lasted less than a heartbeat.
Then it vanished.
The forest returned. The moonlight returned. The cold night wind brushed her cheek with the scent of grass.
Shinobu gasped like a drowning person dragged back to air.
Cold sweat soaked her clothing—then, under the tights' function, her body restored to clean dryness in an instant.
Her hand clenched her sword hilt without realizing it.
Then she looked at Eisen—
And horror surged again.
Eisen stood there, but a blood-red mist boiled around him like fire.
It was thick, violent, hot—reeking of iron and gore, as if his blood had been forcibly vaporized out of his body.
And Eisen himself—
His body was drying out, blackening, shrinking, as if burned into charcoal.
Skin cracked. Muscles withered. His posture hunched.
In a blink, he looked like a standing corpse—carbonized and skeletal.
"GUILDMASTER—!!"
Shinobu screamed, voice breaking sharply, all composure obliterated.
Had her attack done this?
Was he dying?!
The "corpse" tried to speak—yet the ruined throat could only produce two grotesque, hollow sounds.
Eisen seemed to pause—then raised a charred hand and gestured for her to calm down.
In the instant the gesture completed—
A reversal happened.
As if time itself rewound, his condition rapidly reversed.
Char fell away. Fresh skin returned. Muscles filled. His posture straightened.
Within a few breaths, Eisen was completely restored.
Only a faint burnt smell in the air proved it wasn't imagination.
Shinobu's nerves finally snapped out of their death-grip. She exhaled like she'd been holding her breath for a lifetime, fingers loosening from the hilt, trembling.
Eisen rolled his neck with a series of crackling pops as if re-settling into his own body.
Then he spoke with a helpless, almost amused sigh:
"…Your world's power system is really unfriendly to outsiders."
Seeing Shinobu's confusion and fear, Eisen stopped joking and explained.
"I basically understand your world now."
"Simply put: the core medium—the true supernatural foundation here—is blood."
"Blood…?" Shinobu repeated softly.
It made a certain sense. Muzan turned humans into demons through his blood; blood demon arts even carried the name.
"Yes. Blood."
Eisen continued.
"Let's start with how Demon Slayer swordsmen 'grow stronger.' In your world, blood has a unique role: it is the only bridge connecting physical reality and personal will."
"The higher the quality of blood—and the faster it circulates—the greater the force by which will can interfere with matter. Strength, speed, and even the 'rule-bending' phenomenon you call techniques—all come from that bridge."
Shinobu's eyes lit like violet crystal.
She blurted the answer.
"Breathing techniques?!"
Eisen's explanation pierced straight to the heart of it.
Breathing techniques increased oxygen in the blood and drove circulation and pulse at abnormal rates—exactly matching his model.
And the "elements" displayed by sword forms—waves, flame, lightning—felt real to those who had stepped into that realm. Even if ordinary people might mistake it for airflow, light, or illusion, those who practiced knew it was something more.
Eisen nodded.
"Exactly. Breathing techniques are the most direct expression of this rule."
"And demons are stronger for the same reason. Their blood quality is terrifying—nonhuman vitality and curse included. Their altered bodies can push circulation to the extreme limits of biology. High blood quality plus extreme flow lets their obsessions and desires reshape reality into what you call blood demon arts."
Shinobu nodded. It fit her understanding perfectly.
But she still couldn't forget what had just happened.
"Then… what about your condition just now?"
Eisen scratched the back of his head, looking a bit sheepish.
"After I understood the 'blood as bridge' rule, I tried to see if I could move within it—just a little."
He spread his hands.
"Turns out… I pushed too hard. This world is extremely exclusionary. I'm an outsider—I don't have 'citizenship' here. To force my will into the system, I had to spend more blood and increase circulation."
He pinched his fingers close together.
"My circulation got… a bit too fast."
"The result: my blood literally ignited, blew out of my body, and carbonized everything on the way. That's what you saw."
Then he added, almost casually:
"But the effect wasn't bad. For a moment, I squeezed into your world's framework and projected my will into reality. The strength I reached should be near your world's first tier—probably only slightly weaker than Muzan."
"Only slightly weaker than Muzan…?"
Shinobu went still.
That apocalyptic "projection" had nearly crushed her soul, and Eisen claimed that was only "slightly below" Muzan?
Her voice trembled.
"Is Muzan… truly that strong?"
Eisen's expression turned fully serious. He nodded.
"Yes. His pressure won't look like mine, but his interference with reality will be even stronger. I can't fully deploy my own power here without destroying the world. I can only approach your world's ceiling."
"And Muzan… is a native product of this world. He sits at the top of that ceiling by default."
Shinobu's face drained of color.
If that was true, what did a thousand years of sacrifice mean? What did hope even mean?
Despair crept into her like ice.
Eisen saw it instantly and stepped closer, voice warming.
"Hey. Don't give up that fast. I'm not done. I still have good news."
Shinobu lifted her eyes numbly, as if bracing for a final sentence.
Eisen looked directly into her eyes.
"My good news is: your world is not a simple, mundane world with no supernatural foundation."
Shinobu's pupils tightened.
"What…?"
Eisen's tone was firm.
"I suspected it. Your demonstration and my own test confirmed it. Your world was contaminated—long ago—by a higher being."
"A higher being… contaminated?" Shinobu repeated, her heart racing.
"Yes."
Eisen's gaze seemed to look past time itself.
"Far in the past, this was likely a normal world that followed physical law. No supernatural."
"But something—someone—entered it. A being powerful enough to travel freely between worlds… perhaps through the gaps between them. It may have passed through, lingered briefly, then left. Not necessarily with intent to destroy."
His voice grew heavier.
"But its existence alone is a contamination source. When it departed, it left behind a trace. For that being, it might have been insignificant—like a grain of sand left in a footprint."
"But for your world, that 'grain' contained enough authority to twist rules, to provide soil for the supernatural to grow… to birth the distorted lifeform you call demons… and to give blood this bridge-like function."
Eisen inhaled and delivered the core conclusion.
"If my perception is right, the trace it left—the contamination source—the root that twisted your world and ultimately produced all of this…"
He locked eyes with Shinobu.
"…is the Blue Spider Lily."
"Blue Spider Lily—!"
Shinobu cried out, shock detonating in her mind.
The legendary flower Muzan had hunted for a thousand years… the key he believed could conquer the sun…
Was the very contamination left behind by a being above this world?
Join here to read ahead.
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Uma Musume, but My Cheat Power 230
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Multiverse Crossover: The Perf 66
My Cyberpsycho Girlfriend 65
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The Violent Girl Group Is Beat 120
Uma Musume: The Horse Girl Who 67
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Reincarnated as a Demon, Skill 70
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Transmigrated as Sukuna 75
Checking In in Demon Slayer 80
The Reincarnating Trainer of Tracen Academy 85
I Refuse to Become a Heroic 70
My Best Friend Into a Slime? 65
A Saiyan Stands Above Marvel 70
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Tanya Starts from Re:Zero 65
Why did they assign me to Uma 65
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DanMachi: Emiya the Giant Hero 55
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Honkai's Otherworld? Wait—Who Are You People?! 45
Emiya Shirou, Determined to Slay Every Curse and Evil Spirit 45
The Uma Musume Who Became 40
I'm Definitely Not the King of 45
After Maxing Out Every Class 45
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