Faced with Kobe Hikaru's "request," Ubuyashiki naturally had no intention — and no reason — to refuse.
The Demon Slayer Corps existed for one purpose: to kill Demons.
Every sword and every swordsman existed for that purpose alone.
And now, a powerful yokai had come bearing both the intelligence and the strength to kill Kibutsuji Muzan — even if Kobe Hikaru had never asked, Ubuyashiki would have offered him a Sun Blade regardless, simply to improve the odds of cutting down vengeful Demons.
For a Demon Slayer Corps that, in this era, had no Breathing Style to rely on, the Sun Blade was of critical importance.
But what mattered was never the blade itself — it was the craft of forging it, and the raw materials used.
And yet…
The forging of a Sun Blade, however, was bound by a fixed quota.
The raw material wasn't scarce to an extreme degree, but it wasn't plentiful either, and combined with the difficulty of forging and the heavy attrition rate, every blade had to be commissioned in advance.
The wait ran anywhere from ten to twenty days.
Kobe Hikaru couldn't afford to wait that long.
So he decided, in the end, to go himself to the place where the Demon Slayer Corps forged its Sun Blades.
He would forge the blade — himself!
One day would be enough.
To this,
Ubuyashiki still made no objection.
Judging by his manner, he seemed almost… relieved to grant it?
Understandable enough.
Kobe Hikaru was a yokai, true, but he was a yokai who had come bearing a letter from that legendary smith himself — and one should not forget that Totosai, the very master craftsman from whom the Corps' Sun Blades originated, had been a yokai too.
"Let the Kakushi escort you there, then!"
Ubuyashiki Rikiya said at last.
And he left the seven Hashira present no room whatsoever to object.
…
The so-called "Kakushi" were the Demon Slayer Corps' support division.
As an organization that had hunted Demons for centuries, the Corps' overall strength wasn't large — no more than three hundred Demon-slaying swordsmen in any given generation, and no more than a thousand members in total, scattered across the length of the land.
No uniforms, no armor — nothing to compare with the finest armies of the great daimyo.
Yet it still had everything it needed to function.
Among its ranks, the front-line Demon-slaying swordsmen suffered an extremely high casualty rate, and the requirements to become one were correspondingly severe — a candidate had to pass a trial deep within a mountain called "Mount Fujikasane," ringed in wisteria flowers and holding a handful of caged vengeful Demons, surviving seven days and seven nights within it to prove their ability before they could take up the role.
It was a trial with no guarantees and a brutal death toll: pass, and you lived; fail, and you died.
But not every member of the Corps was required to serve on the front line.
The senior swordsmen responsible for testing and training recruits weighed their ability, but weighed their own willingness even more—
Members who couldn't or didn't want to sit the final selection, who couldn't become front-line swordsmen, instead handled the transmission of intelligence, medical care, disposal of the dead, and every other unglamorous task in support of the fight.
They wore masks, never gave their real names, and operated under aliases.
These were the Corps' Kakushi.
The one escorting Kobe Hikaru to the Swordsmith Village went by the alias "Cho."
A single character.
Before setting out, Kobe Hikaru glanced once at Cho.
Since Yoriichi's wife was due to give birth any day now, Yoriichi hadn't come along this time.
It was just him and this clearly female girl.
The Kakushi called Cho was short, noticeably shorter than Kikyo, but her stride was fast — quick little steps ticking along behind Kobe Hikaru, her slender legs pumping as if wound by a spring, the wisteria-patterned hem of her white robe flaring with every step.
She wore a mask patterned after a butterfly.
Below the bridge of her nose, her face was bare — lips pressed tight, wearing the look a young person gets when confronted with something far stronger than themselves: pride tangled together with envy.
"May I ask, Master Hikaru."
"You said you only need one day to forge a Sun Blade—"
"Mm."
That was indeed what Kobe Hikaru had told Ubuyashiki.
"Is that... true?"
"Mm."
She paused. "That 'mm' means…?"
Kobe Hikaru glanced at the girl again, thinking she seemed to be talking rather a lot.
Not that it mattered.
He'd treat it as a way to pass the time.
"It means it's true."
He walked on, his long white hair drifting in the morning mountain wind, a sedge hat slung behind his back, a straw cloak wrapped over his gray robes.
Cho hurried after him a couple of steps, and when she spoke again, her tone carried more caution than before:
"The smiths of the Swordsmith Village… might be difficult to deal with. They're very stubborn about matters concerning blades, and they don't take kindly to outsiders claiming one day is enough. Once, our master invited a very skilled onmyoji there, who said he could speed up the forging. In the end—"
"In the end, what?"
"In the end, they threw him out. They said he'd ruined the iron's temper."
Kobe Hikaru turned his head to look at her.
"The iron's temper."
He turned the phrase over once, then nodded. "That has some insight to it."
Anyone could say that all things possess a spirit.
But those who truly understood it were exceedingly rare.
Having a System of his own, Kobe Hikaru understood this deeply — he'd heard no small number of complaints from his own possessions.
Cho blinked, caught off guard by his answer, and it took her a moment to respond. "So you mean… it really can be done in one day, but without ruining the iron's temper?"
"Mm."
"Then… how do you do it?"
Kobe Hikaru didn't answer right away.
He walked over to an old pine leaning out beside the road, stopped, and pressed his right palm flat against its bark.
Cho stopped as well, watching him, bewilderment plain on her face.
After a moment of silence, Kobe Hikaru withdrew his hand and walked on.
"Even if I told you, you might not understand."
Cho stood frozen for two seconds, then trotted after him. She didn't press further, just walked half a step behind him, occasionally shooting him a quick glance, as if turning something over in her mind — or holding back something she wanted to say.
It was probably whatever message Ubuyashiki had told her to relay to Kobe Hikaru.
Kobe Hikaru paid it no attention at all.
Along the way, the girl who went by Cho kept starting to speak and stopping herself, again and again.
She wanted to give her warning but couldn't find the right moment, and it quietly frustrated her.
She wanted to force the words out, but didn't dare — her master's instructions had been clear: this one, though a "yokai," was a guest of guests, and rudeness toward him was absolutely forbidden!
But Kobe Hikaru actually knew this girl.
Though only half her face was visible, he could still recognize her.
Just not this version of her, from this era.
He knew another version of her — or, in the terms of this world, what should be called her next life.
Shinobu Kocho.
The Butterfly Hashira from the main storyline of Demon Slayer: Kimetsu no Yaiba, the one who always wore a dangerous smile, the girl swordsman who used poison in place of a blade, carving cracks into Demons' undying bodies through medicine alone.
He'd long since confirmed it: reincarnation was real in this world.
Setting Kikyo aside for the moment.
There were incarnations of Bishamonten here, relics of gods and buddhas, and beings like Tsugikuni Yoriichi who came from somewhere and were bound for somewhere else.
Reincarnation itself wasn't strange.
What was strange was that he'd run into, of all things, the person who would one day become the Butterfly Hashira in her next life.
He studied her for a moment and said nothing of it.
There was nothing worth saying.
Her present was her present; her next life was her next life.
Let her walk her own road.
…
The Swordsmith Village wasn't on any map.
The way there had to be walked out by feel — a stretch of dirt road, a stretch of mountain trail, through two bamboo groves, before finally turning onto an old stone path nearly swallowed by weeds.
Without a guide, the road would have been genuinely hard to find — even for Kobe Hikaru, relying on "throwing stones to test the path."
Before Kobe Hikaru even saw the cooking smoke, he smelled the iron.
It was that scent of iron and stone fused together, hot and fresh from the forge.
Faint, but unbroken, as if it drifted on the wind from the deepest heart of the valley.
Cho walked a couple of steps ahead and glanced back. "We're almost there. Someone will meet us at the village entrance."
She paused.
"Master Hikaru, if it's not too much trouble... could you be a little more polite with the smiths?"
"I'm always polite."
Cho glanced at him, something unspoken lingering in her eyes.
Kobe Hikaru ignored her and kept walking.
The people of the Swordsmith Village received Kobe Hikaru properly, courteously, with impeccable manners.
The village head's surname was Ishida, a man in his fifties, with graying hair; his hands, deformed from years of forging, remained nimble nonetheless.
Those hands rested on a teacup, steady enough that not a single ripple disturbed the tea.
He had read Ubuyashiki's letter and confirmed its authenticity.
His expression was one of respect.
"We already received word from our master ahead of time about Master Hikaru's request."
His voice was very low. "I hear you're an old acquaintance of Master Totosai. It's a shame our teacher has passed and cannot receive you."
He was, after all, only human — something both Kobe Hikaru and Totosai had already guessed.
Before finishing, Village Head Ishida added:
"Still, you should know that forging a Sun Blade — from ore selection to forging, to quenching, to polishing — the whole process takes ten days at an absolute minimum. Sometimes the iron doesn't cooperate, and it can drag on to half a month, even a full month."
"I know."
Kobe Hikaru sat across from him, his crimson oni eyes calm, his tone calmer still. "That's why I don't intend to forge it your way."
The smith master's fingers curled slightly.
"Then... what method did you have in mind, sir?"
"I know the ore for the Sun Blade lies in the mountain behind the village… I'll go up myself to choose the iron stone, and then — in one day — I'll finish it myself."
A silence fell over the Swordsmith Village, everyone exchanging glances, lasting at least a quarter of an hour.
In the end, it was Cho who broke it, letting out a soft, quiet sigh.
She'd known it would go this way.
People of great ability always tended to be unconventional.
Let alone a yokai.
…
Still, out of regard for Ubuyashiki — or more precisely, out of regard for Totosai standing behind Kobe Hikaru — the smiths held their tongues in the end, curious to see just what this "outsider" intended to do.
The mountain stood behind the village.
Not especially tall, but dense with growth.
The veins of Scarlet Crimson Ore lay, just as Kobe Hikaru had known, at the very peak of the mountain — closest to the sun. Baked by the blazing sun, the stone there ran darker than elsewhere, taking on a faint orange-red glow in the morning light.
Only from years of exposure to that blazing sun could it carry the sun's own energy within it.
Kobe Hikaru went up alone.
No one from the Swordsmith Village followed. They only stood at the mountain's foot, watching from a distance as that gray-clad back climbed higher.
Cho walked with him as far as the boundary.
"Would you like me to go in with you?"
"No need."
"Alright. There's nothing dangerous in there, but please be careful all the same. I'll wait out here for you to come out."
She didn't press further, retreating to the foot of the mountain to wait, her eyes behind the mask watching him vanish among the trees' shadows.
…
Kobe Hikaru spent a full day in the mountain.
But he did nothing at all — no forging, no hauling ore, not even drawing his sword.
He only walked.
From one stone to another, from one vein to another rock face — wherever he walked, he'd stop, crouch down, and press his palm against it.
Sometimes he lingered a long while.
Sometimes he'd only pat it once or twice before rising and moving on.
Occasionally, he would speak.
His voice was so quiet the forest wind swallowed it whole; only he knew what he'd said.
The stones responded with the faintest of stirrings.
A pebble rolled twice. A bubble rose from a crack in the rock. The color of a stretch of ore wall deepened by a shade.
All of it was exceedingly subtle.
If you weren't paying close attention, there was Nothing at All.
But the smiths waiting at the foot of the mountain noticed.
They took turns keeping watch beyond the treeline, glancing every so often into the depths of those shadows, still unable to make sense of what they saw — only exchanging looks, brows furrowed, swallowing their confusion.
Village Head Ishida crouched on a rock beyond the treeline, watching in silence for most of the day.
In the end, he only drew on his pipe and let two words drift out into the evening mountain wind.
"Extraordinary man."
Cho heard it and said nothing.
She stood at the mountain's base the entire day, even taking her midday meal there, never once leaving.
She couldn't say exactly what she was waiting for.
She just felt that something was about to happen, and she didn't want to miss it.
…
By noon the next day.
The sun had climbed to its zenith, and the mountain air had warmed into a lazy, sunbaked haze, as if even the air itself had slowed down.
The smiths ate when it was time to eat and rested when it was time to rest, and someone still kept watch at the mountain's foot — though with less energy than the day before. They'd waited a whole day already; surely they wouldn't have to wait another?
"It's moving."
A young smith keeping watch by the trees spoke up suddenly.
Everyone looked up at once.
Among the shadows of the trees, Kobe Hikaru emerged.
Pale long hair, gray robes, crimson oni eyes glinting faintly in the noon sun.
The instant he stepped past the treeline, he stopped, turned, bowed his head toward the mountain's heart, and said something very quietly.
His voice was so faint that only Cho, standing nearest, caught three words of it, and even then only faintly.
"My thanks for the trouble."
Then he raised his head and walked toward the smiths.
The smiths exchanged glances; no one knew who those words had been meant for.
"Sir, what is this—"
Village Head Ishida rose to his feet, forgetting even to hold his pipe. "You've chosen it already? But where's the ore—"
He couldn't finish the sentence.
Because a sound came from the mountain.
Not the ordinary sound of a landslide, and certainly not falling rock — but something smaller and finer, yet clear enough in that silent valley to send a chill crawling up every spine.
The iron and stone were moving.
Not being dug up. Not being carried. Moving — on their own.
The Scarlet Crimson Iron Sand scattered through the veins, the ore embedded deep within the rock walls — piece by piece, they broke loose from their places and gathered, flowing slowly down through the earthen channels and cracks within the mountain's heart.
Like a slender crimson stream, they poured out from the mountain's belly and flowed into some of the old workshops the smiths of the village kept on the slope.
No one lit the forge.
The flame in the furnace kindled itself, its color purer than usual, an almost impurity-free red, steady without the slightest flicker.
The bellows swelled on their own.
The anvil beside the forging table shifted a fraction, as if straightening itself into place.
Throughout the whole workshop, everything that should have required a human hand had begun to move by itself.
The iron ore melted in the flame, turning into liquid crimson molten metal, then, guided by some invisible force, flowed into the mold, cooled, took shape, and was folded and hammered again and again by itself — the sound of each fold even, the rhythm steady, every strike landing precisely where it should, without the slightest deviation.
Not a single hand touched anything through the whole process.
The smiths stood outside the workshop, at its threshold, in the yard, watching it all in complete silence.
The old smith's pipe slipped from his hand and fell to the ground. He didn't pick it up, his clouded eyes fixed on the self-forging furnace, unblinking for a very long time.
Cho stood three paces from Kobe Hikaru, watching the same sight.
As a Kakushi of the Demon Slayer Corps, she didn't need to fight on the front line, but she'd still grown used to seeing things ordinary people never had the chance to.
Blood. Death. The Demon's inhuman strength.
But this scene still shook her.
Iron, forging itself.
Fire, burning according to its own will.
A Sun Blade, with no craftsman lifting a finger, was going from raw ore to finished form, step by step, at a speed that didn't belong to this world.
"This is..."
She swallowed quietly, forcing down her astonishment, and asked, "How are you... how are you doing this?"
Kobe Hikaru didn't answer right away.
He simply rested a hand on a nearby workshop pillar, palm flat against the wood, his tone casual.
"Objects have spirits."
"You talk to them. Tell them what you intend to do. Tell them you need them. Tell them you know they're capable of it."
"Then, you wait."
"Wait for what?"
"Wait for them to decide to help you."
That was, in fact, everything Kobe Hikaru had spent the day doing.
He'd learned the craft of forging from Totosai, but its true essence had never lain on the surface.
It lay instead in the subtle art of combining persuasion with the forging itself.
That was the real reason he'd come.
He wouldn't ruin an object's temper — or, put another way, its spirit.
He'd only let them, of their own accord, help him complete this step.
This was what it meant for all things to possess a spirit.
This was what it meant that those who found the Way received much aid.
This was Kobe Hikaru's own Way.
Cho stood in stunned silence for a moment.
She glanced at the pillar beneath Kobe Hikaru's hand — she'd have sworn the wood's grain had brightened just a shade, taking on a gloss no timber should have, something almost like happiness — then looked back at the roiling heat of the furnace and the self-operating forge within.
Just then, the Scarlet Crimson iron stone in the workshop let out a soft, crisp ring, as if in reply.
Kobe Hikaru tilted his head toward the sound, and the corner of his mouth twitched.
"The rest is up to them now."
With that, he drew his hand back from the pillar, turned, walked toward the veranda, and found a place to sit.
He moved with easy, unhurried calm, as if everything had gone exactly as expected — as if none of it were anything remarkable at all.
The old smith stood at the workshop entrance for who knew how long, before finally bending slowly to pick his fallen pipe up off the ground.
He said nothing.
He only held the pipe in his hand and exhaled softly.
In that breath was thirty years of forging, and the astonished, weighty sigh of a man seeing something he'd always taken for legend proven real, so effortlessly, for the very first time.
He'd heard rumors like this before.
He'd heard that the very greatest master smiths could forge things so seamless, so natural, they seemed to have grown that way on their own.
That was true, heaven-surpassing craftsmanship.
And now, he'd seen it.
Though what he'd witnessed was something else entirely, not quite the same.
Yet it arrived at the very same place, by an entirely different road.
The finest technique of forging had never been about forcing iron to take shape by human will.
It was letting iron shape itself, following its own will.
He knew this truth. Every smith knew it. They spent their whole lives chasing it, and when they couldn't catch it, they passed the words down to the next generation, so the chase could continue.
But the man before him had done it, effortlessly, in a single day, with nothing more than a few words spoken to stone.
"Remarkable."
He said it, all the same.
Just one word, but his tone carried no flattery, only a gravity that came from the bone.
Cho heard it and said nothing either.
Her gaze moved from the Sun Blade taking shape inch by inch inside the workshop, to the gray-clad figure sitting on the veranda with his eyes closed in rest, and finally settled on that stern, expressionless face.
Yet his eyes were shining.
As one of the Corps' support staff, tasked with aiding the front-line swordsmen, she'd studied medicine, learned a little about ore, and even understood some basics of forging. She knew what those iron stones had stored within them—
Hundreds, even thousands, of years of unbroken sunlight, day after day.
What they had stored, perhaps, was patience.
And what the yokai before her had just taught those stones… was, as it happened, that very same thing.
Only his patience pointed in a different direction.
One day.
One instant.
Sun Blades that should have taken at least ten days, if not a full month, to forge — finished in less than a quarter of an hour.
Yes.
Not one blade.
But a whole handful — of Sun Blades!
____
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