The night was pitch-black, yet flames lit up half the sky.
This was a field of burning ruins.
The blazing fire burned as fiercely as the sun, silently and violently devouring everything. The redwood pillars that once formed this exquisite courtyard collapsed within the sea of flames, while thick black smoke coiled above the wreckage, bringing with it surging waves of heat.
The gust lifted the girl's bangs.
Sui watched expressionlessly as the place she had grown up in was reduced to ashes by the torch she herself had set.
Her eyes shone brightly in the darkness. Her irises carried a strange, pale azure hue, within which flickered a deep crimson light—like a torch ignited upon an icy wasteland. At the corners of her eyes stretched a faint streak of scarlet, vivid as blood under the glow of the flames.
In Sui's vision, the world was broken down into fractured points and lines—only black and red, things that could be cut and things that could not.
And those twisted monsters… in her eyes, they were riddled with cracks.
She cut them apart, killed them, and in the end burned the fallen people to rest with a single fire.
At the very least, they died in silence—seen by others as humans, rather than as the man-eating "demons."
Among them were her family—those who had cherished her, those she had loved. Tonight, they had turned into horrifying demons, and she had pierced their hearts with her own hands.
"I'm truly pitiful… You all died so easily. Where am I supposed to go now?"
The girl let out a soft sigh.
Becoming an orphaned little girl in Japan's Taishō era after once being a well-adjusted youth of the 21st century already sounded absurd enough. Yet something even more absurd had happened—after more than a decade of peaceful living, her world had shattered overnight.
This world truly had creatures called "demons."
Their legends had circulated since the ancient Nara period—beings that walked the night, feared sunlight, and fed on humans.
Sui had once thought they were nothing more than stories to scare children. In her previous life, her grandmother had loved telling her ghost stories in much the same way.
But now she had seen the difference.
The price was everyone's lives.
She let out a breath, an overwhelming exhaustion washing over her.
If not for these eyes, she would have been one of those monsters tonight.
A sharp whistling sound suddenly came from behind.
"Who's there?"
Sui turned back warily. She couldn't be sure whether the powerful demon that had devastated this place might return to admire its handiwork.
Her eerie ice-blue eyes gleamed like something otherworldly.
She locked onto the newcomer—it was a swordsman. Draped in a flame-patterned haori, he carried a white-sheathed katana. His presence was extraordinary, and the red "lines" on his body were so few that she could hardly perceive them.
Sui let out a quiet breath of relief.
As long as it was a human, that was enough.
The swordsman stepped beside her, his eyes sharp and spirited.
"Girl, can you tell me what happened here?!"
His voice was loud, brimming with energy.
"Why don't you tell me who you are first?"
Leaning against a tree, Sui sheathed her bloodstained blade into its redwood scabbard.
How interesting—he looked steady and composed, yet was so full of vigor.
But she was too tired now, too tired even to glance at him. Using those strange eyes drained her as much as running two kilometers had in her previous life.
With the swordsman's arrival, it felt as though her entire body had been submerged in warm water—her nerves relaxing all at once.
"I am a Hashira of the Demon Slayer Corps, here to exterminate demons!"
The swordsman declared loudly, full of spirit.
He maintained his stance for quite some time, but when no response came, he lowered his head in confusion.
"Girl?"
No reply.
She had already fallen asleep against the tree.
Her ink-black hair spilled loose, framing delicate, almost storybook-like features. Wrapped in a deep red kimono, her slender figure seemed even more fragile, her skin as pale and luminous as snow.
The swordsman studied her, forced to admit she was a rare beauty. Even in the capital, where beauty was abundant, she could have lived well relying on her appearance alone.
He turned his gaze to the ruins and the corpses of demons.
What an incredible child.
Alone, she had eliminated demons.
Yet he had observed that the blade in her hand, though fine and sharp, was not one of the special weapons capable of killing demons.
So how had she done it?
Curiosity stirred within him.
He removed his haori, stepped forward, and draped it over her shoulders, deciding to wait for her to wake.
For a swordsman tempered by long training, a night passed quickly.
But for Sui, it felt like an eternity.
The events of last night shook her to her core.
"Today is Sui's birthday! You have to dress up nicely. I specially commissioned this kimono from a craftsman in Kyoto—try it on."
"Wow, is this our beautiful Sui-chan? In the future, so many important people will pursue you! Be careful, don't get sweet-talked away."
"Sui! Run, hurry—no… Sui, welcome home!"
"Rare blood, rare blood! Such delicious rare blood—I've never seen anything this good, hahaha!"
"I'm sorry… Sui, I want to take a bite of you. Is that okay?"
The howls of demons.
The sound of a blade slicing through flesh.
And finally, that person's last whisper to her—
"Sui… thank you…"
The girl opened her eyes. The flame-patterned haori draped over her slipped gently to the ground.
Warm sunlight bathed her face, yet it felt like a different world.
She stared blankly at the ruins.
The flames had long since died out, leaving only charred wooden frames.
Buried there were the people who had loved her most.
"Girl!"
A familiar voice—it was the swordsman. His booming voice could probably be heard across the entire courtyard.
Sui came back to her senses, only now noticing the haori covering her.
"Thank you."
She handed it back.
"It's nothing."
The swordsman put it back on. "My name is Shinjuro Rengoku , a Hashira of the Demon Slayer Corps!"
"The Demon Slayer Corps…"
Sui had heard of them before, part of the same legends as demons themselves. It was said that when the sun set, demons would appear to devour humans—and that demon slayers would rise to kill them and protect the people.
She had once thought it was nonsense. Having grown up in the 21st century believing only in science, not superstition, she had dismissed such tales outright.
But demons were real.
She had killed them herself.
Including her own loved ones.
The moment she looked into their eyes, she understood—once someone became a demon and consumed human flesh, death was the best end they could hope for.
"Can I join?"
The girl asked.
"Hm?"
Shinjuro Rengoku 's flame-like brows furrowed slightly. "A child like you could live a life a thousand times better than in the Demon Slayer Corps!"
He meant it.
With her beauty, even if her family was gone, she could still find someone willing to love and care for her, living a life of comfort among the upper class.
The Demon Slayer Corps was not the best choice for her.
If anything, it was the worst.
Or perhaps, looking at this girl—about the same age as his own children—he simply did not wish for someone so young to face such a cruel fate.
"That kind of choice would make me rot, Mr. Rengoku. I think you understand that."
The girl spoke softly, exhaustion lacing her words.
She looked at him, her eerie eyes opening once more.
"I can bring death to those monsters."
Meeting those strange eyes, beneath their icy, desolate coldness, Shinjuro Rengoku felt an inexplicable urge to flee.
Unbelievable.
So this was how she had slain demons.
As a Hashira who had killed countless demons and witnessed endless tragedy, he understood the value of such power.
There was no reason to refuse her any longer.
"The Demon Slayer Corps welcomes you!"
he declared in a resounding voice.