Three months ago, when Tanjiro and the other two had carried the barely breathing Taka and Rengoku into the recovery facility, Inosuke's heart had suffered a tremendous shock.
He had grown up alone in the mountains since childhood, raised by beasts, and had created his own Beast Breathing. He once considered himself brave and invincible.
But after witnessing more and more strong individuals, that arrogant idea was long gone. Now, it was mostly just to bolster his own courage.
Inosuke was reckless, crude, and unwilling to admit defeat, but he wasn't stupid.
The scene after the Mugen Train derailment three months ago burned repeatedly in his mind:
Kyojuro, covered in blood… Taka, with his chest bones shattered.... Yet even so, they never gave up, fighting until the very last moment!
'The golden-haired aniki was strong, and Torataro was strong too.'
'But even such strong swordsmen could be severely wounded by an Upper Moon Kizuki.'
'And what about me? I could only stand by, waiting for an opportunity to help, spending most of my time in a daze!'
"More! More!" He used all his strength to drag several huge rocks around the courtyard, desperately training his physical power.
"....I couldn't even get involved in a fight like that... I'm still not strong enough!"
A sense of frustration, mixed with a craving to grow stronger, forced him to consider whether his Beast Breathing could be further improved.
So, while Taka was being treated at the Butterfly Mansion, unconscious, he made a decision.
"Hey!" He grabbed a passing Demon Slayer Corps' member and asked gruffly: "Where did Torataro train to become a Hashira?"
"Huh? What Torataro? And why are you wearing a pig mask?"
"Shut up! Torataro is Torataro! Idiot!"
He asked many people, and finally learned from the woman he found hardest to deal with, Shinobu, that Taka trained in a swordsmanship style called Wind Breathing, at the Hayama training ground to the north.
"Wind Breathing?" Inosuke had heard of this school.
When he had joined the Demon Slayer Corps, the Kakushi members had defined his Beast Breathing as a derived school of Wind Breathing, which had annoyed him.
'My own style, Beast Breathing, is someone else's appendage? Damn it!'
'But since Wind Breathing could train that guy Torataro to be so strong, it seemed worth training in.'
So he said goodbye to Tanjiro and the others, and with Oyakata-sama's permission, followed the Kakushi members to Hayama.
'Go there! Find the way to make Torataro strong!'
On this day, he finally arrived at the mountain gate of Hayama.
"Inosuke-san, this is—"
"Boar Rush—!!"
Before the Kakushi member could even finish his sentence, Inosuke roared and charged in!
"Whoa! A wild beast!!"
A young boy sweeping leaves in the courtyard was so frightened he dropped his broom and yelled in panic.
Inosuke paid him no mind, his target directly aiming for the largest main dojo ahead, from which voices could be heard.
Bam—!!!
He rudely burst inside and roared amidst the shocked gazes of the disciples:
"Inosuke-sama has arrived!! Who's the teacher who trained Torataro? I want to train too!!"
His gaze under the boar mask was like a torch, sweeping over the startled group.
In the center of the main hall, a tall, thin, white-haired, and bearded old man with one arm was sitting cross-legged on a cushion, holding a cup of steaming tea in his remaining right hand: "Remember, when breathing, pay attention to the expansion of your lungs. Be sure to...."
At this moment, the instructor of the Hayama training ground, Arasaki Tetsushin, was explaining the secrets of Breathing Styles to everyone.
The intimidating intrusion just now was like a gentle breeze to him… it didn't interrupt his lesson.
Beside him, a young woman in a plain, elegant blue-grey kimono, with a gentle and serene temperament, had just refilled the old man's tea.
Now she also looked up, casting a surprised glance at this uninvited guest.
"Hey hey hey! What's going on? Why is no one paying attention!" Inosuke clamored noisily, making Tetsushin's brows furrow.
Seeing that the disciples' attention was already drawn to Inosuke, he no longer forced it and slowly put down his cup: "Alright, today's lesson ends here. Go practice on your own."
When most of them had left, he finally spoke: "Are you the Demon Slayer Corps' member Oyakata-sama mentioned?"
The day before, he had already received a message from his Kasugai Crow, so he naturally knew a reckless boy would be coming to train. He just hadn't expected....
Tetsushin sized up Inosuke, frowning: "I don't quite understand. You already have your own Breathing Style. Why come to me?"
"My Beast Breathing is naturally the strongest! I just want to know how you trained Torataro to be so strong!" Inosuke thumped his chest, the tusks on his boar mask trembling excitedly:
"Teach me too! I want to defeat an Upper Moon too!"
Tetsushin narrowed his eyes slightly and sighed softly. His eyes were full of the helplessness of dealing with trouble.
He already knew about Taka's narrow defeat against the Upper Moon. He was very worried about this disciple and sent a Kasugai Crow to the Butterfly Mansion every two days to ask about Taka's treatment.
To be honest, it was simply unbelievable to him that Taka could fight an Upper Moon Kizuki until dawn.
In his heart, Taka was still that cold, distant little guy. He never imagined he would grow so fast....
But to claim this was his own achievement… Tetsushin was not that shameless.
".....Taka is a strong and hardworking child. His strength today is not because of me. You've come to the wrong person." Tetsushin picked up his tea, took a sip, and said calmly: "Since you already have the power to slay demons, go fulfill your duty. Don't disturb the peace here."
This casual rejection instantly ignited Inosuke's temper.
"Shut up, old man!" Enraged, he directly charged at Tetsushin, his right fist swinging with a vicious wind: "I'll make you talk!"
Faced with this rock-shattering punch, Tetsushin's figure didn't even sway.
The moment the punch wind arrived, he forcefully deflected the inside of Inosuke's wrist with the hand holding his teacup—
Bam!!
This tiny movement directly caused Inosuke's entire body to lose balance. His forward charge was abruptly cut short. His large frame tumbled awkwardly in mid-air like a clumsy top!
Not only did he miss his punch, but his whole body crashed into the sliding door behind him.
"Ouch—!!"
He landed hard, face-first like a pig, scrambling up miserably.
"Pfft." Rika beside him covered her mouth and laughed softly.
'Yes, yes! This feeling!' Inosuke's gaze under the boar mask burned fiercely.
'Back when I had provoked Torataro, that guy had also used a very tiny movement to show me the flaw in my attack.'
'What did he say? Something about openings, momentum… forget it all!'
'This one-armed old man definitely had something. Learn from him! Then I'll definitely be stronger than Torataro!'
Tetsushin slowly stood up, looking down at the miserable Inosuke on the floor:
"Enough, stop making a fuss. The strength you're so obsessed with, if it's just imitating others' movements, will only lead you to lose yourself." He helplessly waved his hand and turned to walk outside:
"Kenichi! See our guest out."
Kenichi, called by name, quickly responded. He sympathized with the pig-masked figure on the ground as he hurried to pick up the pair of serrated blades that had flown off.
"Wait! You damn… good old man! Don't go!"
Inosuke struggled to his feet, not bothering to dust himself off, and quickly shouted:
"I... I can't go back like this! Torataro is still lying there!... I have to become stronger! Stronger than everyone!"
"I won't just stand by and watch my comrades fall, powerless to help, ever again!"
"Please! Teach me!"
"If you won't teach me... I'll just train here myself! Until I master it!"
He stiffened his neck, like a stubborn wild boar cornered on a cliff edge, expressing his most stubborn determination with his fiercest posture.
Under the boar mask, his eyes were even slightly red from extreme frustration.
Tetsushin's footsteps paused at the corridor entrance leading to the inner chambers, but he didn't turn back.
He was silent for a moment, finally only turning his head helplessly to look at Rika:
"Sigh... you take care of him."