"Hmm?"
Rubbing his eyes, Sishu realized that daylight had already arrived outside.
"Did I fall asleep just now?"
Recalling what had happened before he dozed off, he suddenly noticed something strange. At some point, without even realizing it, he had mastered Total Concentration Breathing.
It was clearly mentioned in the booklet handed to him by Yoriichi.
Once a person truly grasped the Total Concentration Breathing technique, they would unconsciously maintain the breathing even while asleep.
"This sensation… it really is different from before."
Even though he had only just learned Sun Breathing, Sishu's body had already undergone a massive transformation.
He felt brimming with vitality, as if an endless reservoir of energy surged within him.
His muscles were tighter, more defined, his gaze sharper than ever, and his breathing flowed with natural ease and rhythm.
He had taken yet another solid step toward becoming the world's strongest.
As the morning sun climbed higher, he stepped into the training field and began his daily regimen.
Sword swings, sandbag strikes, sprints, boulder pushing…
Hour after hour passed. He had completed every part of his training routine.
Clenching his fist, Sishu gave a slight shake of his head, a hint of disappointment in his eyes.
His strength had grown to such a degree that these exercises no longer offered meaningful challenge or progress.
Despite the time and effort, his body felt no exhaustion at all.
Just as he was pondering new ways to train and push his limits, a scattered group of people nearby caught his attention.
Turning his gaze in their direction, he saw them all heading toward an open square.
"That place… if I remember correctly…"
With curiosity piqued, he stepped forward and stopped a young girl walking toward the gathering.
She appeared to be about ten years old, freckles lightly dusting her cheeks, with two pigtails on either side of her head. She looked as though she had just woken up, her eyes still clouded with sleep, expression unfocused.
"Hello, beautiful. Mind if I ask why everyone's heading to the square?"
Still grumpy from being woken up, the girl's temper flared as soon as someone blocked her path.
She was about to lash out with a few harsh words, but the moment she turned around and saw Sishu's polite smile, she froze.
Handsome, courteous, and confident, he instantly stole her attention. Whatever anger she had disappeared without a trace, tossed into the depths of the ocean.
Unlike his master, Sishu was not aloof or cold.
In just a few simple sentences, he learned everything he needed from the girl named Hanori.
As he suspected, the square was reserved for breathing technique lectures. Usually, these sessions were led by swordsmen who had trained in breathing techniques for several years.
But today was different.
A real Pillar from the Demon Slayer Corps had arrived.
The Flame Hashira himself—Rengoku Kyojuro!
It was the arrival of the Flame Hashira that allowed younger children like Hanori, who had not yet reached the age threshold, to experience breathing techniques in advance.
Normally, only those twelve years and older were allowed to learn the breathing arts.
"The Flame Hashira himself is teaching breathing techniques today? That sounds interesting."
"It's a good chance to hear someone else's perspective. I might as well listen in."
Following the flow of people, Sishu entered the square.
He picked a secluded spot and sat down quietly, scanning his surroundings.
In the center of the square stood a man in his twenties.
His long hair shimmered in hues of gold and red. Beneath his sharp brows gleamed eyes full of vitality and conviction.
A subtle, warm smile curled at the corners of his lips. His entire aura radiated fierce enthusiasm and boundless energy.
This was the current Flame Hashira—Rengoku Kyojuro.
After observing him for a moment, Sishu could not help but marvel at the strength of the Rengoku family's genetics.
Whether it was Kyojuro himself, Rengoku Shinjuro from centuries later, or even Rengoku Senjuro who lacked talent in swordsmanship, every member of that family looked nearly identical.
Once the crowd had filled the square, Kyojuro cleared his throat and raised his voice.
"Ladies and gentlemen, I sincerely thank you all for coming to today's lecture on breathing techniques."
"Let us not waste time. Let us begin!"
"First, I would like to ask—what is the principle behind breathing techniques?"
Faced with a direct question from a Hashira, everyone immediately fell into deep thought.
This was a rare opportunity to make an impression before one of the elite. Some might never get such a chance again in their lives.
Before long, several participants began offering answers.
"Is it about drawing invisible energy from the air?"
"No way. It has to be about awakening the energy hidden within our bodies. Like… a personal cosmos?"
"Umm, I… I forgot because I got nervous…"
Kyojuro waved to the nervous student and offered a reassuring smile.
"I'm afraid none of your answers are quite correct."
"Even among those who have received prior instruction, your explanations are vague at best."
"However, I am confident that with time and experience, you will come to truly understand."
He laughed heartily at his own words, his voice echoing across the square.
Watching him laugh alone in the middle of the crowd, Sishu could not help but sigh inwardly.
"So this is how the Rengoku family teaches?"
Sensing the discussion needed to move forward, Sishu decided to step in and break the silence.
"The principle behind breathing techniques is to expand the lungs to their fullest. This allows the blood to receive an intense supply of oxygen in a short period of time."
The moment those words left his mouth, the entire square fell silent.
"Whoa. That explanation sounds so scientific."
"Who is that guy? He's ridiculously handsome, articulate, and looks even younger than me."
"Don't you recognize him? The moment I saw him, I knew. He's my future husband."
Ignoring the last comment from a particularly enthusiastic girl, Kyojuro raised his hand to silence the crowd.
Sishu's explanation had stunned him. Even he could not find a single flaw in the logic.
"Excellent explanation. I suggest everyone take a moment to reflect on what he said."
A minute passed quietly.
Kyojuro clapped his hands and continued.
"Now that we understand the principle behind breathing techniques, let me explain how to actually perform them."
Everyone in the crowd immediately straightened their backs and paid close attention.
Even Sishu focused intently, eager to learn from one of the best.
"From my personal experience, the process goes as follows. First…"
In just a few minutes, Kyojuro shared everything he had personally learned and refined about breathing techniques.
He even included some of his own tips and tricks, sparing his audience from making the mistakes he had made in the past.
"You can now try it yourselves. Use what I just taught to feel the rhythm and apply the breathing technique."
Folding his arms, he added with a smile, "If you have any questions, feel free to ask."
It had to be said, members of the Rengoku family might have a flare for the dramatic.
But when it came to teaching, they were always patient and genuinely passionate.
For every question asked, Kyojuro gave thoughtful and detailed explanations.
Soon, everyone in the square closed their eyes and began to attempt the technique.
Kyojuro nodded, satisfaction lighting up his face.
They were weak now, only just beginning to explore this vast new world.
But he firmly believed that some among them would one day support the entire Demon Slayer Corps.
While watching the students, his gaze was suddenly drawn to a boy.
His striking appearance alone made him stand out. But what truly caught Kyojuro's attention was the boy's breathing.
Unlike the others, his breaths were steady, powerful, and perfectly controlled.
The rhythm was precise, his body moving in flawless harmony.
It was almost unbelievable that a child no older than eight could breathe with such mastery.
Even Kyojuro himself had not reached this level of control when he first learned.
Just as Kyojuro's curiosity deepened, coughs began to echo throughout the square.
Gradually, the others opened their eyes, many disrupted by lack of control or shortness of breath.
To sustain Total Concentration Breathing for an extended time required more than talent. It demanded relentless training and willpower.
Soon, only one person remained with their eyes still closed.
Sishu.
Inhale. Exhale. Inhale. Exhale.
He was lost in the world of breath, completely unaware of what was happening around him.
"Breathing technique detected. Enhancing efficiency."
"Nine thousand twenty… Nine thousand forty… Nine thousand sixty…"
With each passing moment, Sishu's understanding of breathing deepened further.
His unwavering focus and endurance drew every pair of eyes in the square.
Whether it was first-time learners or experienced trainees, they all looked at him the same way.
A mixture of awe, disbelief, and something bordering on fear.
In that single moment, their thoughts became one.
This guy… is he even human?