Three months earlier, when Tanjiro and the others carried the dying Asuka and Kyojuro into the infirmary, the sight struck Inosuke's heart like a hammer.
He had grown up alone in the mountains, raised by beasts, creating his own Beast Breathing. He had always believed himself to be invincible.
But after witnessing more and more powerful warriors, that arrogant belief had long since vanished. Most of the time now, it was only something he told himself to keep his courage up.
Inosuke was reckless, rough, and fiercely competitive, but he wasn't stupid.
The scene from three months ago replayed again and again in his mind: the moment the Mugen Train derailed.
Kyojuro Rengoku was covered in blood. Asuka's chest bones had been completely shattered. Yet even so, neither of them gave up. They fought until the very last moment.
The golden-haired big brother was strong. Torataro was strong too.
And yet even swordsmen that strong had been gravely wounded by an Upper Rank demon.
What about him?
All he could do was stand to the side, waiting for a chance to help. Most of the time, he had just stood there in a daze.
"More! More!"
He strained with all his might, dragging several massive boulders across the courtyard as he desperately trained his strength.
"...In a battle like that, I couldn't even step in... I'm still not strong enough!"
The frustration mixed with his desire to grow stronger forced him to confront a question.
Was there still a way for his Beast Breathing to evolve further?
So when Torataro lay unconscious in the Butterfly Mansion, he made his decision.
"Hey!"
He grabbed a passing Demon Slayer and growled, "Where did Torataro train to become a Hashira?"
"Huh? Who's Torataro? And why are you wearing a boar head?"
"Shut up! Torataro is Torataro, you idiot!"
He asked many people in a row, until finally the woman he had the hardest time dealing with, Shinobu Kocho, gave him the answer.
Asuka practiced a sword style known as Wind Breathing, trained at the Hayama Training Grounds to the north.
"Wind Breathing?"
Inosuke had heard of it before.
When he first joined the Demon Slayer Corps, the Kakushi had categorized his Beast Breathing as a derivative of Wind Breathing. He had been quite dissatisfied about that.
My own Beast Breathing being treated like someone else's offshoot? What a joke!
But if Wind Breathing could train someone like Torataro into such a powerful fighter, then maybe it was worth learning after all.
So he said farewell to Tanjiro and the others. With the Master's permission, he followed a Kakushi member toward Hayama.
Go there.
Find the secret that made Torataro so strong.
On this day, he finally arrived at the gates of Mount Hayama.
"Mr. Inosuke, this is—"
"CHARGE AHEAD!!!"
Before the Kakushi member could finish speaking, Inosuke roared and burst through the entrance.
"Wah! There's a wild beast!"
A teenage boy sweeping fallen leaves in the courtyard dropped his broom in fright and shouted.
Inosuke ignored him completely, heading straight for the largest building ahead, where voices could be heard.
BANG!
He barged straight into the room and roared at the stunned disciples inside.
"Lord Inosuke has arrived! Who's the teacher that trained Torataro? I want training too!"
His sharp gaze burned from beneath the boar mask as he scanned the room.
At the center of the hall sat a tall, thin old man with white hair and beard, missing his left arm. He was seated calmly on a cushion, holding a steaming cup of coarse tea in his remaining right hand.
"Remember, when breathing, pay attention to the expansion of your lungs. Be sure to..."
At that moment, the instructor of the Hayama Training Grounds, Tetsushin Arisaki, was explaining the secrets of breathing techniques.
The dramatic intrusion seemed like nothing more than a breeze to him and did not interrupt his lecture.
Beside him stood a young woman in a simple blue-gray kimono. Her temperament was gentle and composed as she had just refilled the old man's tea.
Now she lifted her eyes, looking at the unexpected guest in surprise.
"Hey! What's going on? Why's no one answering me?!"
Inosuke's noisy shouting finally made Tetsushin Arisaki frown slightly.
Seeing that all the students' attention had already been drawn away, he stopped the lesson and slowly set down his teacup.
"That's enough for today. Go practice on your own."
After most of the students had left, he finally spoke.
"So you're the Demon Slayer sent by the Master?"
Two days earlier, his Kasugai Crow had already delivered the message. He knew that a reckless youngster would soon come to train here.
But he had not expected...
Tetsushin Arisaki looked Inosuke up and down, his brows furrowing.
"I don't quite understand. You already have your own breathing style. Why come here?"
"My Beast Breathing is obviously the strongest!"
Inosuke puffed out his chest proudly, the tusks on his boar mask trembling with excitement.
"I just want to know how you trained Torataro to be so strong!"
"Teach me too! I want to defeat an Upper Rank!"
Tetsushin Arisaki narrowed his eyes slightly and sighed, his gaze full of weary helplessness.
He had already heard that Asuka had narrowly lost to an Upper Rank demon.
He worried deeply for that disciple. Every two days he sent his Kasugai Crow to ask the Butterfly Mansion about Asuka's condition.
To be honest, hearing that Asuka had fought an Upper Rank demon until dawn sounded almost unbelievable to him.
In his heart, Asuka was still that cold and distant child who kept everyone at arm's length.
He had grown far faster than expected.
But to claim credit for that growth?
Tetsushin Arisaki was not shameless enough to do that.
"Asuka is a strong and hardworking child. His strength today is not because of me. You've come to the wrong person."
He took a sip of tea and spoke calmly.
"Since you already possess the power to slay demons, go fulfill your duty. Do not disturb this quiet place."
The casual rejection instantly ignited Inosuke's temper.
"You annoying old man!"
In a burst of anger, he rushed forward and threw a powerful punch that howled through the air.
"Let's see if you still refuse to talk!"
Facing the mountain-crushing blow, Tetsushin Arisaki didn't even move.
At the moment the punch approached, he simply used the hand holding his teacup to tap the inside of Inosuke's wrist.
BANG!
The tiny movement instantly disrupted Inosuke's balance.
His forward momentum was cut off completely, and his large body spun through the air like a clumsy top.
Not only did the punch miss, he crashed straight into the sliding door behind him.
"Oww!"
He landed face-first in a humiliating heap before scrambling upright.
"Pfft."
Rika covered her mouth and laughed softly.
Yes! That's exactly the feeling!
Inosuke's eyes burned with excitement beneath the boar mask.
When he had challenged Torataro before, the guy had also used tiny movements to expose the flaws in his attacks.
What did he call it again?
Something about openings and momentum... whatever, he'd forgotten!
This one-armed old man definitely had some skill.
If he learned from him properly, he'd definitely become stronger than Torataro when he went back!
Tetsushin Arisaki slowly stood and looked down at the disheveled Inosuke.
"Alright, enough of this."
"The strength you obsess over—if it only comes from copying others' movements, you'll lose yourself."
He waved his hand helplessly and turned toward the doorway.
"Kenichi. Show the guest out."
The named student responded quickly, casting a sympathetic glance at Inosuke before running off to retrieve the pair of serrated blades that had flown away.
"Wait! You... you old... respectable old man! Don't leave!"
Inosuke scrambled to his feet, shouting without even brushing the dust off himself.
"I... I can't just go back!"
"Torataro is still lying there!"
"...I have to become stronger! Stronger than everyone!"
"I won't stand there helplessly watching my comrades fall ever again!"
"Please! Teach me!"
"If you won't teach me... then I'll train here by myself! Until I succeed!"
He stood there stiffly like a stubborn wild boar driven to the edge of a cliff, expressing the most stubborn determination in the fiercest way possible.
Under the boar mask, his eyes were even slightly red from his unwillingness to give up.
Tetsushin Arisaki stopped at the entrance to the inner corridor but did not turn around.
After a moment of silence, he simply glanced sideways toward Rika with a helpless expression.
"Sigh... You take him under your wing."