"Hey, where's Instructor Tetsushin?"
The moment he entered Hayama, Sanemi Shinazugawa casually grabbed a disciple wearing a light-green kendo uniform and barked the question at him in a rough, booming voice.
He had come to visit his mentor, Arasaki Tetsushin.
Since becoming a Hashira, his schedule had been packed—constant missions, constant bloodshed. Being able to return here under the excuse of an assignment, to the place that had once tempered him, was a rare form of relaxation for him.
Unfortunately, ordinary disciples didn't recognize Sanemi Shinazugawa at all. Faced with his ferocious appearance, they were so frightened their legs trembled, words failing them entirely, let alone answering his question.
"He's in the back mountain, Brother Sanemi."
"Oh? Rika."
A breeze swept past. Sanemi's grip loosened slightly, and in the next instant Rika's figure flashed by, gently steadying the terrified disciple and guiding him aside.
Rika looked at the shaken student with concern. "Are you alright? Are you hurt?"
"Give me a break. I wouldn't hurt people in my teacher's dojo." Sanemi smacked his lips, his tone still rough. "The back mountain? Don't tell me the old man found another Tsuguko (successor)."
After seeing the flustered disciple off, Rika smiled and turned back to Sanemi.
"Not exactly. It's an interesting child. Teacher has been guiding him in the back mountain for the past two years."
Two years?
Sanemi's fierce brows twitched. He bared his white teeth in a grin filled with beastlike interest.
"Sounds like a decent seedling. I've gotta see what kind of material he is."
The back mountain was Arasaki Tetsushin's ground for the highest-intensity, most core training—normally reserved only for those he deemed truly qualified to inherit the essence of Wind Breathing.
As a former Wind Hashira, Arasaki Tetsushin held the right to take in successors—his most trusted disciples.
Compared to ordinary Demon Slayer Corps members and trainees, successors received far greater resources and support: better weapons, equipment, and training conditions. Naturally, they were also expected to possess exceptional talent.
In other words, a successor's potential was almost synonymous with the possibility of becoming a future Hashira.
Sanemi himself had once shed endless sweat and blood in that very place. Hearing that a new candidate had entered the back mountain instantly ignited his competitive instincts.
Without alerting anyone else, he followed a narrow path alone toward the depths of the back mountain.
The closer he drew to the secluded training ground encircled by ancient trees, the more restless the air became.
The wind was growling. Sword intent was slicing invisibly through the air.
Soon, he saw the figure.
At the center of the clearing, a boy was swinging his sword.
Each movement was swift and precise. Every slash tore through the air, whipping fallen leaves into spiraling currents around him.
The boy's bare upper body was taut with muscle, sweat glistening in the sunlight as it dripped onto the earth beneath his feet, soaking it into dark stains.
His breathing was deep and steady. Each inhalation seemed to draw in all the surrounding wind, while every exhalation carried searing heat and a low hum of air friction.
One glance was enough for Sanemi to tell—the body before him had been forged through extreme training.
"His fundamentals aren't bad." Arms crossed, Sanemi leaned against the thick trunk of an ancient tree, openly scrutinizing him.
He could see the embryonic form of Wind Breathing within the boy's swordplay. Though it hadn't yet reached the level of formal forms, that ruthless drive and all-or-nothing impact somehow felt… oddly agreeable.
Like catching sight of a kindred shadow.
At the same time, Sanemi's senses—sharper even than Arasaki Tetsushin's—picked up on the aura surrounding the boy.
It wasn't the airflow generated by Wind Breathing.
It was something extremely subtle, yet viciously sharp and violent.
If he had to describe it, it was like countless invisible, hungry fangs opening and closing in the air, carrying a primal urge to tear apart and devour everything.
Sanemi had never felt this kind of fluctuation from any Wind Breathing user. It didn't belong to Breathing Techniques at all, yet the boy seemed to forcibly blend it into his swordsmanship, forming a unique, highly destructive style.
"Interesting…"
The interest in Sanemi's eyes deepened, the corners of his mouth curling upward unconsciously.
He could tell the boy had already noticed his presence. The tension in his back and the sudden sharpening of the sword wind made it clear—the intruder had been locked onto instantly.
Asuka had indeed sensed him immediately.
Sanemi Shinazugawa's presence was far too conspicuous. In the quiet back mountain, it was impossible not to notice.
Over the past two years of training, fragments of Asuka's shattered, chaotic memories had slowly returned.
He had come to realize that although he had become a flesh-and-blood person in this world, he was ultimately different from others.
Asuka could sense a kind of soul energy within himself—something he called spiritual particles. He could also feel the same energy coming from Instructor Arasaki and Miss Rika.
However, when he tried to explain this concept to Miss Rika, she couldn't perceive what he described at all. Rika believed it was simply the natural breathing talent the teacher often mentioned—something unique to Asuka that others couldn't experience.
Such cases weren't unheard of. After all, even the Demon Slayer Corps' Breathing Techniques originated from a natural breathing method that no one else could master, later evolving into what they were now. So Rika didn't find it strange.
Thus, in addition to practicing Wind Breathing, Asuka spent his spare time trying to control this spiritual power and integrate it into his sword techniques.
Perception of spiritual pressure—this was one of the most basic applications of that power.
The white-haired man standing with crossed arms atop the tree radiated an immense, ferocious spiritual pressure, thick with the stench of blood. It was utterly different from Instructor Arasaki's mountain-like, steady oppression.
But this was still the back mountain of the training grounds. Asuka believed that if it were truly some terrifying demon, it wouldn't appear here in broad daylight without any disturbance.
He forcefully suppressed the surge of unease in his chest. Instead of stopping his training, he raised his vigilance to the highest level.
"So strong… incredibly strong! Stronger than Miss Rika! It even feels… stronger than Instructor Arasaki…"
"Hey!"
Sanemi Shinazugawa finally spoke, his voice loud and impatient, carrying his habitual commanding tone.
"Kid! You about done warming up? Stop flailing around and let me see what you're made of!"
Before Asuka could reply, Sanemi's figure vanished from the treetop with a sharp whoosh.
Almost entirely by relying on his perception of spiritual pressure and pure instinct, Asuka subconsciously activated Wind Breathing and slashed fiercely toward his side.
Clang—!!
A deafening crash rang out. Sanemi had already caught the strike with his unsheathed sword, slamming it hard against Asuka's wooden blade.
Watching Asuka's reaction, Sanemi didn't get angry—instead, he found it even more amusing.
That stubborn, wary, feral gaze was like a mirror.
He snorted, rolled his neck, and a series of sharp cracks echoed out.
"Oh? Not bad at all…"