Chapter 7: Breath of Wind
That strike was nothing like the crude brawling of street thugs.
Nor was it anything like the clumsy hacking Asuka had relied on when swinging the Asauchi with nothing but brute force and desperation.
This slash felt more like a resonance between the human body and nature itself—
the ultimate power a human could unleash, poured wildly into heaven and earth!
The wooden sword rose from low to high—
and a storm was born.
"…Teacher's really serious today," Rika murmured.
Centered on Arasaki Tetsushin, a tornado made purely of violent airflow erupted from the ground!
RUMBLE—!!
The crushing wind pressure poured out along the path of his wooden blade, sweeping across more than half the training field in an instant!
Snow grit mixed with dust from the ground, forming a massive sand-and-snow vortex several meters wide that shot straight toward the sky—like a roaring, earth-yellow python baring its fangs at the heavens!
Along the edges of the tornado came shrill cutting noises. Razor-sharp wind blades darted visibly within it, and Asuka had no doubt that touching it even once would tear his flesh apart instantly.
Moments later, the howling vortex slowly dissipated. The snow and dust that had been flung skyward rained back down, forming a perfectly clear circular zone around Arasaki Tetsushin.
He gradually withdrew his stance, the wooden sword angled toward the ground, his breathing returning to calm.
Arasaki turned his deep gaze toward the stunned Asuka and spoke in a low, powerful voice.
"Did you see that?"
"If you want to kill demons, wild strength and a bit of street-born viciousness aren't enough."
"If you're willing, I can teach you the Breath of Wind. It will give you the power to fight demons—but you must also shoulder the responsibility that comes with it…"
"Asuka—do you have the resolve to become a member of the Demon Slayer Corps?"
Resolve…?
Asuka froze for half a second—then dismissed the idea almost immediately.
Killing demons?
He didn't really feel anything about that.
He didn't know where demons came from, but to him, demons eating people felt no different from dogs fighting over scraps or wolves devouring sheep—just another cruel rule of this world.
He had already repaid the old man's blood debt with his own life. Other demons meant nothing to him.
Demon Slayer Corps or not—
he didn't care what those people wanted to do.
But power…
This old man possessed real, tangible power—power that could be learned.
If Asuka wanted to live—
to live better, safer—
then he needed strength.
"…Fine," he said after a pause.
"How many of those monsters do I have to kill to earn the training?"
Arasaki Tetsushin looked at him deeply.
The wildness in the boy's eyes hadn't faded—like a lone wolf dragged back into a pack. That relentless will to survive was the foundation of a powerful swordsman…
…but also a danger.
Still—
in these increasingly turbulent times, the Demon Slayer Corps needed fresh blood.
After a moment's hesitation, Arasaki made his decision.
"You don't need to trade anything."
"If you've made up your mind, then starting tomorrow—stay and train with us."
And so—
Seventy-Eight Asuka,
a stray dog from the very bottom of Rukongai,
remained at the Hayama training grounds.
---
In the beginning, Arasaki Tetsushin taught him nothing about sword forms or combat.
Every day began instead with the fiercest morning wind atop the mountain.
Arasaki gathered all the disciples and had them sit cross-legged on the freezing outdoor training field, eyes closed, sensing the cold and violent mountain wind.
"The Breath of Wind is the most agile and swift of all styles—
as unpredictable and ferocious as the gale itself!"
"Feel the air enter your mouth and nose, flow through every inch of your airway, fill your lungs—then slowly exhale!"
"Don't rush your breathing! Imagine yourself as a bellows—each inhale must expand to its absolute limit! Each exhale must empty completely, like a hurricane scouring the land!"
Asuka listened, puzzled.
What's so hard about breathing?
He followed the instructions for a few cycles—
—and Arasaki's wooden sword snapped sharply against his diaphragm, precise and merciless. Pain exploded through him, stealing his breath entirely.
"Too shallow!" Arasaki barked.
"Rhythm! Maintain a steady, powerful rhythm!"
Asuka forced himself back upright, teeth clenched, pushing himself to follow the instructions to their extreme.
He quickly learned why this was hell.
In the raging mountain wind, the air itself felt like knives pouring into his chest. Yet they were required to breathe far deeper and faster than normal, deliberately sensing every trace of airflow.
It was as if countless invisible needles were stabbing his trachea and lungs over and over. His chest felt like it was being torn apart; every breath was like blades scraping through his throat.
In less than ten minutes, his vision darkened. His ears rang violently. He doubled over, coughing uncontrollably.
"Hah! Can't even handle this much pain and you want to master the wind?" Kenji scoffed.
He was also seated and breathing—but his progress was far deeper than Asuka's, leaving him far less miserable.
He didn't bother hiding his ridicule.
Arasaki allowed it to happen.
Silently, he observed—watching as Kenji deliberately provoked the feral stray boy he found so irritating.
Asuka paid no attention to Kenji's mockery. He simply wiped the saliva drawn from his mouth by violent coughing with his sleeve, steadied his breathing, and tried again.
Compared to the days when survival itself was uncertain—when he lived like a stray dog driven from place to place—what did this little bit of pain amount to?
Arasaki watched quietly.
He saw the near-obsessive persistence clinging to Asuka's body—the clumsy, heavy breathing, the brute effort, the refusal to let go. It was the tenacity of a wild beast struggling to survive.
The old man's expression remained grave.
This child… has a vicious streak.
For his goal, he'll squeeze out every last drop of strength he has…
One day.
Two days.
Three days…
Asuka became the first to arrive at the training grounds—and the last to leave.
Before the morning frost had fully melted, he was already seated cross-legged on the freezing stone slabs. And long after everyone else had departed, he still hadn't stirred from his meditative breathing.
A tearing pain spread through his lungs. Sweat soaked his clothes, then chilled rapidly in the mountain wind, clinging to his skin with bone-piercing cold.
He endured it.
Sometimes, after pushing himself beyond exhaustion, he would collapse unconscious on the icy stone. Rika would find him during her patrols and drag him back to his room.
The next day, he would appear again—
on time,
eyes sharper than before.
Kenji's laughter gradually turned into silence.
Silence turned into puzzled observation.
He watched Asuka fall again and again—
and climb back up again and again.
This wasn't training.
It was a gamble with his life, as if he were burning himself away just to exchange it for the faintest chance at becoming stronger.
That kind of ruthlessness made Kenji feel pressure.
Even… admiration.
When Asuka finally managed to sustain the breathing for over half an hour amid searing pain—without passing out—Arasaki at last handed him his first training wooden sword.
"Starting tomorrow," the old man said,
"we begin physical training."
That didn't mean release.
It meant worse suffering.
---
Inside the training hall, Arasaki demonstrated the most basic grip.
"Without a solid foundation, even the most dazzling techniques are castles built in the air. Carve that into your bones."
Thus began Asuka's training in monotony so severe it bordered on madness.
Chop.
Slash.
Lift.
Thrust.
Again and again.
Day after day.
Both hands gripping the heavy wooden sword, he swung precisely according to Arasaki's demands—angle, force, posture.
Every strike had to match the rhythm of his breathing.
Inhale—store power.
Swing—release.
Exhale—settle.
Form must be correct.
Breathing must be synchronized.
After completing their assigned repetitions, Kenji and the other trainees moved on to footwork drills or sparring.
Only Asuka remained—
like a tireless machine—
standing in place, swinging the wooden sword again and again.
His arms felt filled with molten lead. Each lift was agony. The rough handle tore his palms open, blood soaking into the grip. Sweat flowed into the wounds, bringing searing pain. His lower back ached so badly it felt ready to snap.
"Enough! Today's quota is done! Are you trying to ruin your body?" Kenji finally shouted after one session, unable to hold back.
Asuka didn't slow.
Sweat ran down his clenched jaw and dripped onto the wooden floor beneath his feet. He said nothing.
He didn't know what muscle soreness was.
He only knew that when a thug's club came down, his back hurt far worse.
Morning.
Noon.
Dusk.
Night.
Even deep midnight.
Thousands.
Tens of thousands.
Hundreds of thousands.
The blisters on his hands burst, scabbed over, and eventually hardened into thick calluses.
These days lasted seven months.
Until one day, Kenji looked at him—with unmistakable respect—and said:
"…Asuka. You're incredible. The teacher says that starting tomorrow, you're ready for field training."