"Alright! From here on, we'll begin your training!"
Kyojuro Rengoku spoke with his usual bright enthusiasm the moment he saw Chiba Yang.
"Yes. I will work hard."
Chiba Yang nodded firmly.
Soon after, he followed the Flame Hashira to the training grounds within the headquarters of the Demon Slayer Corps. When they arrived, two people were already there.
Both were girls.
One of them had long black hair with purple-tinted tips in her bangs. A butterfly hairpin rested on her head, and her purple eyes carried a calm yet sharp gaze. She wore the standard Demon Slayer Corps uniform, over which she draped a haori patterned like butterfly wings.
The other girl also had black hair and purple eyes. She wore the Demon Slayer uniform paired with a knee-length black pleated skirt and white boots. A white cloak fastened with a dark pink ribbon hung over her shoulders.
The two seemed to be practicing sword techniques.
When they noticed Rengoku approaching with Chiba Yang, they paused their training.
"Rengoku, you're back. How did the mission go?"
Shinobu Kocho sheathed her blade and stepped forward with a gentle smile.
Rengoku did not answer immediately. Instead, he glanced back at Chiba Yang.
Seeing his reaction, Shinobu seemed to understand something.
Her smile faded slightly, replaced by a look of sympathy as she glanced toward Chiba Yang. Beside her, Kanao Tsuyuri remained the same as always—quiet, smiling faintly, though her expression carried a hint of absent-mindedness.
"This is my new Tsuguko. His name is Chiba Yang!"
Rengoku broke the heavy silence first, introducing the boy with his usual bright and energetic voice.
Then he turned toward Chiba Yang.
"Yang, this is the Insect Hashira of the Demon Slayer Corps. She is a remarkable warrior who has developed poisons capable of killing demons, overcoming the disadvantage of physical strength in battle. She is someone worthy of great respect!"
His tone was as cheerful as ever.
"Insect Hashira."
After hearing the introduction, Chiba Yang bowed respectfully toward Shinobu Kocho.
Rengoku had already explained the hierarchy within the Demon Slayer Corps to him earlier. As the Hashira were the strongest members of the organization, Chiba Yang felt it was only proper to show them respect.
"Oh my, Rengoku gives me far too much credit."
Shinobu smiled modestly.
"You don't need to be so formal either, Yang. You can simply call me Sister Shinobu from now on."
"Yes, Sister Shinobu."
Chiba Yang nodded respectfully again.
Shinobu could not help but smile helplessly at his overly polite attitude.
"And this is my Tsuguko, Kanao Tsuyuri."
Shinobu gestured to the girl standing beside her.
"You two seem about the same age. How old are you, Yang?"
"Fifteen," Chiba Yang replied.
"You're actually a year younger than Kanao."
Shinobu sounded slightly surprised.
"Kanao should be participating in the upcoming Final Selection soon, correct?" Rengoku asked.
"Yes," Shinobu answered with a nod.
"Then give it your all!"
Rengoku encouraged loudly.
Kanao simply smiled at him as she always did.
"Well then, our training for today is nearly finished. We'll head back first."
After saying that, Shinobu left the training grounds with Kanao.
Once they were gone, Chiba Yang turned to Rengoku.
"Rengoku-sensei, what exactly is the Final Selection you mentioned earlier?"
"The Final Selection is the final examination required to become a member of the Demon Slayer Corps," Rengoku explained.
"The trial takes place on Mount Fujikasane, a mountain inhabited by demons. Participants must survive there for seven days. Anyone who succeeds will receive their own Nichirin Blade and officially become a Demon Slayer."
Chiba Yang frowned slightly after hearing this.
It sounded… rather simple.
The green demon he fought earlier had been easily defeated.
Although he later learned that demons could only truly die from sunlight or a Nichirin Blade severing their necks, he still felt it would not be particularly difficult.
Moreover, the Final Selection only required surviving on the mountain for seven days.
That meant someone could technically pass without killing a single demon.
Perhaps the demons there are much stronger, he thought silently.
"However, it is still too early for you to take part in the Final Selection."
Rengoku suddenly spoke again, his voice bursting with energy.
"You must first earn my approval before participating!"
"Therefore—training begins now!"
"Start with two hundred push-ups!"
"Yes, Rengoku-sensei!"
Chiba Yang responded immediately and dropped to the ground without hesitation.
At the same time, he instinctively adjusted his breathing.
A faint stream of white vapor escaped from his lips.
Rengoku froze for a moment when he saw it.
Breathing Technique?
But… I haven't taught him that yet.
Unsure of what he had just witnessed, Rengoku stepped closer and began observing carefully.
"113… 114… 115… 116…"
Chiba Yang continued doing push-ups with intense focus.
His breathing rhythm was incredibly steady. Even after completing over a hundred repetitions, not a single drop of sweat appeared on his face. His expression remained calm and relaxed.
After watching more closely, Rengoku finally confirmed it.
It was indeed a Breathing Technique.
Not only that—it did not resemble any specific style. More astonishingly, it had already reached an advanced state.
Total Concentration Breathing… Constant.
The boy was maintaining Total Concentration Breathing unconsciously at all times.
Rengoku fell silent.
The situation had clearly exceeded all his expectations.
"197… 198… 199… 200!"
Chiba Yang finished the final push-up and stood up.
Still, there was not a single bead of sweat on his face.
He looked completely relaxed.
"Rengoku-sensei, I've finished. What's the next training exercise?"
Rengoku stared at him in disbelief.
He still had not stopped breathing that way.
This truly is Total Concentration Breathing—Constant…
After a moment, Rengoku finally spoke.
"Yang… when did you learn a Breathing Technique?"
Chiba Yang blinked in confusion.
"I've never learned one. You haven't taught me yet, Rengoku-sensei…"
Then he suddenly seemed to realize something.
"Oh! Are you referring to the breathing method I use when training?"
He scratched his head, suddenly understanding.
"I figured that out when I was around five or six years old. By adjusting my breathing, my strength and endurance improve a lot. I can do things that normally wouldn't be possible. That way I could help my mo—"
His voice faltered.
Memories surfaced in his mind again.
Pain spread through his chest.
But he quickly forced himself to steady his emotions.
Mother would want me to keep living well…
Just like the way I felt when I saw her try to give up before…
After a brief silence, he looked back at Rengoku.
"Is that what you call a Breathing Technique?"
"Yes."
Rengoku nodded slowly.
"It is indeed a Breathing Technique."
"And not just any technique."
"You have already reached a very advanced state."
"Total Concentration Breathing—Constant. Maintaining Total Concentration Breathing throughout the entire day."