The courtyard in the back of Mount Momoyama was brightly lit.
Steam rose from the hot pot, blurring the figures of the old man and the girl. Only the rapid movement of chopsticks through the broth could be seen clearly. Though Shinjuro had once remarked that Sui's appetite was pitifully small, she had walked all day without a proper meal, slain a demon at night, and then been dragged by Kuwajima into running several kilometers up the mountain.
At a time like this, even the smallest eater would turn into a glutton.
Kuwajima hadn't exaggerated—his cooking truly surpassed that of the innkeeper. Even though Sui never got to taste that bowl of noodles, she was convinced of it.
The old man sat cross-legged to the side, holding his cane.
He quietly examined the sword Sui had been carrying, which he had borrowed while she ate. The moment he picked it up, he felt its weight—it was noticeably heavier than ordinary blades. The scabbard was crafted from fine redwood, reinforced with brass fittings. A red cord was wrapped near the mouth, and a string of red prayer beads hung from the hilt.
The once-bright crimson of the scabbard had faded into a darker red over time. Combined with the fine scratches along its surface, everything about it spoke of age—it truly deserved to be called an ancient blade.
He slowly drew it.
The blade shimmered like clear water, releasing a soft hum. Near the guard, he clearly saw an inscription in ancient script:
"Yatsugashira Tsushita Yomi Taidō."
Calamity.
The old man frowned.
The moment he read the inscription, it felt as though boundless killing intent seeped out from the blade. This murderous aura wasn't directed at humans or demons—it targeted all living things that could be cut.
This wasn't just a valuable antique.
It was a bloodthirsty cursed blade.
Kuwajima couldn't help but glance at the girl. Though her beauty carried an eerie edge, her demeanor was gentle—she didn't seem like someone prone to slaughter.
Where had she gotten such a weapon?
"Does this sword have a name?"
he asked, hoping to glean something from it.
"I don't know."
Sui shook her head. The blade had been worshipped by her family for generations, but they only knew its inscription. Its story had been told to her by the woman who raised her.
"This is a cursed blade. It has taken countless lives."
The old man spoke plainly.
"I know."
"You know?"
"Yes. I know it's inauspicious. Otherwise, it wouldn't have been placed on an altar for worship."
Her indifference left Kuwajima momentarily at a loss.
"To fight man-eating demons, using an even more vicious blade… I think that's reasonable."
"If you rely on those eyes of yours, then this blade…"
The old man trailed off. He wasn't certain whether this sword could truly kill demons.
"From now on, use a Nichirin Blade whenever possible. I'll keep this sword for now—it will also reduce the risk of your eyes being exposed to the Twelve Kizuki."
He didn't return the blade. He feared the killing intent it carried might affect her mind.
Sui didn't object. She had thought the same. No matter where or when, one should know how to conceal their strengths. If she already knew Breathing techniques or proper swordsmanship, she wouldn't have needed to rely on her eyes to deal with weaker demons.
"How much do you know about the Demon Slayer Corps?"
Seeing her calm and composed, Kuwajima's opinion of her rose again.
"An organization of swordsmen dedicated to slaying demons."
Sui answered, "Lord Shinjuro told me that the highest-ranking swordsmen are called Hashira. Below them are ranks from Kinoe down to Mizunoto. There's also the Ubuyashiki family, who serve as the core of the Corps."
"And breathing techniques?"
"Nothing at all."
She shook her head.
"Mm."
The old man stood, his expression turning solemn.
"Then tell me—how strong were the demons you faced compared to ordinary people with no combat training?"
Sui thought for a moment.
Demons far surpassed humans physically. Against them, ordinary people were little more than prey.
"They can't be fought. It's a one-sided slaughter."
"Exactly. The human body is far weaker than a demon's. With human strength alone, we cannot contend with them—let alone kill them. That's why Breathing techniques and Nichirin Blades were developed."
"These are techniques passed down since the Warring States period. Through Breathing, humans gain powerful, resilient bodies capable of defeating demons. And with Nichirin Blades, a demon can be truly killed once its head is severed."
"You are an exception."
The old man added,
"But I will not teach you as one. I will train you as an ordinary swordsman in training. If you rely solely on your eyes without proper skill, then when you face something like a member of the Twelve Kizuki, you'll be no different from an ordinary person—completely helpless."
Seeing her still deep in thought, Kuwajima assumed she was dissatisfied.
"What is it?"
Sui frowned slightly.
"What exactly are the Twelve Kizuki? Could you explain in more detail?"
She still remembered the moment she cut down that woman—the first time that person had shown such vulnerability. In her arms, she had whispered something before dying.
A name.
"The Twelve Kizuki are the twelve direct subordinates of the progenitor of demons—Muzan Kibutsuji. They are the strongest among all demons he has created…"
The old man suddenly stopped.
An overwhelming aura of death had filled the space.
As a former Hashira, he was no stranger to death—but before those ice-blue Mystic Eyes, even he felt insignificant.
Under her gaze, for the first time in his life, he felt a chilling certainty—
As if this was what the end of life looked like.
"Muzan Kibutsuji…"
he heard her murmur.
In Shinjuro's letter, it had been mentioned—her family had turned into demons on her birthday, even trying to devour her.
Had she encountered Muzan himself?
Kuwajima's heart trembled.
Then—
Thwack.
He tapped her head with his cane.
"Eh?"
The icy glow vanished instantly. Sui clutched her head—no exaggeration, that really hurt.
"I think I understand now. Judging by your reaction, the one who turned your family into demons was likely the progenitor himself—Muzan Kibutsuji, who hasn't appeared for a thousand years."
"This is the Demon Slayer Corps. Everyone here wishes to cut off Muzan's head with their own hands. You need to stay calm."
Sui nodded obediently.
Quite sensible, the old man thought with a hint of relief. He had been worried she might rush off seeking revenge.
The Demon Slayer Corps had existed for a thousand years. Over that time, countless talents had emerged. Generations of Hashira had come and gone.
And yet—
They had only ever replaced the Lower Ranks of the Twelve Kizuki.
The Upper Ranks had never changed.
Could this girl ever reach Muzan?
Kuwajima didn't know.
It was a hope they all carried—but one they also knew was little more than a distant dream.
"Go get some rest. Your room is the first one in the courtyard—it's already prepared."
"I'll begin teaching you breathing techniques tomorrow."
He waved her off.
Sui bowed slightly and closed the door behind her.
These days, the Demon Slayer Corps was in a transitional period. Since his retirement, not a single swordsman using Thunder Breathing had risen to take his place as the Thunder Hashira.
His old friend, Sakonji Urokodaki, had also retired to become a trainer. Yet not long ago, a new Hashira using Water Breathing had emerged.
Kuwajima couldn't help but feel a little envious.
Wind, Flame, Water, Stone, Thunder—the five original Breathing styles had almost never lost their successors throughout history.
And yet now, Thunder Breathing had no heir.
A bad premonition stirred in his heart.
But recalling the feeling of being gazed upon by those ice-blue eyes, that unease gradually faded.
No Thunder Hashira?
Wasn't one just delivered right to his doorstep?