Chapter 18 — The Colorless Blade
The morning mist was scattered by the wind. The training grounds were already packed early, though most people were yawning and grumbling nonstop.
"Raise your arm a bit higher. Put some strength into it."
Asuka passed by Kenji, showing no mercy just because they were familiar. He poked Kenji's forearm with the hilt of his asauchi, correcting him without hesitation.
Kenji grimaced, his body instinctively tensing as he struggled to straighten his arm the way Asuka demanded.
"Imagine the wind as an extension of your arm…"
Moving on to the next trainee, Asuka again shared his understanding without holding anything back. His standards, however, were strict—far stricter than most people could meet.
Rika, who was walking toward the training grounds, smiled faintly at the chorus of complaints echoing across the field.
Since Master Arasaki had handed the responsibility for morning training over to Asuka, everyone had been waking up earlier with each passing day.
These days, Asuka continued polishing his sword forms with Master Arasaki while also trying to share his insights with the trainees.
Rika could tell—ever since Asuka became an official member of the Demon Slayer Corps, the teacher had begun thinking about retirement.
Either Asuka would be trained as a tsuguko, a successor fit to become a future Pillar… or he would eventually inherit the Hayama training grounds themselves.
As for Rika, she only wanted to remain quietly at Hayama, tending to the graves of Brother Masachika and Sister Suzune.
"Asuka, there's a visitor in the main reception room," she called out. "They asked for you by name."
A cheer instantly erupted across the training grounds.
A visitor? Looking for me?
Asuka was puzzled. He barely knew anyone here—and it was still early in the morning. Who could it be?
He slid open the door to the reception room. Morning sunlight slanted in, illuminating Master Arasaki seated at the head, and the visitor before him.
The man wore a plain kimono, over which hung a loose outer robe patterned with sun motifs. A large straw hat sat atop his head, decorated with several dangling wind chimes.
When Asuka entered, the man raised his head, revealing a strangely shaped mask—round-faced, puff-cheeked, with an ambiguous half-smile.
A long, narrow wooden box wrapped in gray cloth rested neatly before him.
"Asuka, this gentleman is—"
"My name is Haganezuka."
Before Arasaki could finish, the man cut him off. His voice sounded dull and muffled from behind the mask.
"I personally forged the blade meant for Seventy-Eight Asuka. And I personally delivered it."
A swordsmith.
Asuka closed the door and, at Arasaki's signal, bowed to the man before taking his seat.
When he had rushed to Fujikasane Mountain earlier, the Final Selection had already ended. All he could do was choose a remaining piece of Scarlet Ore and hand it over to the Kakushi. They told him it would take at least fifteen days for the blade to be delivered.
"Thank you. I'm—"
"This is the Nichirin Blade! A blade forged by me!"
Haganezuka cut him off again and began unwrapping the cloth on the box without another word.
Asuka exchanged a glance with Arasaki, who could only shake his head helplessly as Haganezuka continued:
"Nichirin blades are forged from ores closest to the sun—Scarlet Crimson Iron Sand and Scarlet Crimson Ore. They absorb sunlight and use it to slay demons. Finest materials there are."
"I heard you defeated a demon without using a Nichirin blade. How did you do that?"
At this, Asuka paused.
So Shinsuke and the others had reported everything—including the fact that he'd fought using an asauchi.
He hesitated, glanced at Master Arasaki, then removed the asauchi from his waist and carefully handed it over.
"I just used an old blade that happened to suit me. In the end, it was still the Nichirin blade that took the head."
Though this sword was deeply important to him, Asuka had learned through repeated testing that to anyone else, the asauchi looked like nothing more than a battered, ordinary blade—no special reaction at all.
The moment Haganezuka took it, his arm jerked violently.
He carefully drew the blade partway, scrutinizing the corroded, rust-pitted surface. Then he looked at Asuka again.
Finally, puzzled, he returned the asauchi.
"A very unusual blade… but that's not why I'm here today."
He opened the dark wooden case wrapped inside the cloth and lifted out the long blade, handing it to Asuka.
Like the old Nichirin blade Master Arasaki had lent him before, this sword's scabbard was a plain matte black—no ornate patterns, no decoration—only a heavy, restrained sense of solidity.
Haganezuka stared at the sword in Asuka's hands, waving his arms excitedly as he spoke:
"Nichirin blades are also called Color-Changing Blades! They change color based on the wielder's strength and state of mind!"
"I heard you defeated a vicious demon that could use Blood Demon Art all by yourself! You must be something special! I poured seven full days of my heart and soul into forging this blade just for you!"
"Come on, come on! Draw it! Let me see what color it turns~!"
"Ahhh— maybe blue, right? The blue of the sky, the blue of the wind… or maybe emerald green? Or moon-white?! I'm dying of curiosity—draw it already!"
Watching Haganezuka dance around like a madman, Asuka frowned slightly, then solemnly loosened the scabbard and drew the Nichirin blade with a sharp clang.
Hummm—
As he raised the blade upright, a deep, lingering resonance vibrated through the room, instantly drawing the attention of all three men.
Behind the mask, Haganezuka's eyes narrowed to slits, locked onto the surging aura around the blade. Master Arasaki straightened at once, his gaze turning grave as he focused on Asuka.
At first, a sense of freedom and lightness echoed within Asuka's heart.
Responding to that rhythm, the blade near the guard shimmered with a clear, vibrant green glow.
But in the next instant, a cold, suppressed wave—heavy with darkness—crashed in, violently extinguishing that rhythm.
A sharp flash of icy light burst from the blade.
Then the mutation truly began.
Near the base of the sword, a thick, coagulated-blood-like crimson suddenly spread outward, sticky and ominous, as though the blade had just drunk deeply of life itself.
The red surged upward—and both Haganezuka and Arasaki froze.
Red?
Was it really red?
Before the crimson could fully spread, an even more extreme color erupted.
Black.
A pitch-dark black that seemed capable of devouring everything surged up, entwining with the crimson, relentlessly chasing it all the way to the very tip of the blade.
Black and red formed a sharp yet eerily interwoven boundary along the cold steel.
And yet—
There was not a single trace of the verdant green, pale blue, or any of the lively, wild hues one would expect from a Wind Breathing swordsman.
Then, before the colors could fully stabilize, the two arcs of light canceled each other out—
—and vanished.
What remained was a blade as bright and ordinary as polished steel.
"This is…" Arasaki murmured, deeply puzzled.
"What's wrong, Master?" Asuka asked calmly. "Is black and red bad?"
"…Not exactly," Arasaki replied slowly. "Black is rare. Dual-colored Nichirin blades are even rarer."
This color had never appeared among Wind Breathing users.
In fact, it resembled the blades of Flame Breathing swordsmen—most notably, the current Flame Pillar's blade.
Including himself, Arasaki had seen the swords of four Wind Breathing users with Pillar-level talent. Every single one reflected imagery tied to wind and sky.
But a blade whose color appeared—and then vanished entirely?
That was unheard of.
Haganezuka's reaction was far more extreme.
The strange mask trembled violently, harsh breathing and low growls leaking from behind it, growing louder by the second.
He shook his head, leaned in close to Asuka's blade, and inspected it over and over again.
Finally—
he let out a furious roar that echoed across the training grounds, loud enough for the disciples outside to hear.
"YOU—BASTAAAAARD!!!"