For a moment, Kyojuro Rengoku was completely stunned by Chiba Yang's situation.
During his time in the Demon Slayer Corps, he had met countless swordsmen. Without exception, every one of them only began learning Breathing Techniques after joining the organization. Even then, it typically took months of rigorous training to reach the level of Total Concentration Breathing — Constant.
Yet Chiba Yang had already reached a level that many people considered the end of their training journey.
"Alright," Rengoku said after a moment of thought. "I will demonstrate the sword forms of Flame Breathing for you. Try to use your breathing to perform the techniques."
"At your current stage, the only things left for you to refine are sword techniques and physical training!"
As he spoke, Rengoku walked to the weapon rack in the training yard and picked up two bamboo swords. He handed one of them to Chiba Yang.
"Yes, Rengoku-sensei!"
Chiba Yang replied loudly and obediently.
Holding the bamboo sword, he stood to the side and carefully observed Rengoku's movements. During the days they had spent together, Chiba Yang had noticed that Rengoku's hearing was not particularly sharp, so he intentionally spoke a little louder whenever addressing him.
"First is the First Form of Flame Breathing—Unknowing Fire. This technique launches a sudden charge toward the enemy with explosive momentum!"
As he explained, Rengoku demonstrated the movement.
He adjusted his breathing, planted his right foot firmly on the ground, and gripped the sword with both hands.
In the next instant, he shot forward like an arrow released from a bow. His blade swept horizontally through the air, the fiery slash cutting forward with a sharp whistling sound.
In Chiba Yang's eyes, everything about Rengoku's body during the technique became perfectly clear.
The expansion of his lungs while breathing.
The flow of blood through his veins.
The contraction of muscles.
Every detail etched itself into Chiba Yang's mind.
Chiba Yang stepped forward with his right foot, lowering his center of gravity. Gripping the bamboo sword with both hands, he assumed the exact same stance Rengoku had used moments earlier.
His lungs expanded as he inhaled deeply.
"Watch carefully—"
Rengoku turned around to continue his explanation.
But his words were abruptly cut off.
"Flame Breathing, First Form—Unknowing Fire!"
Chiba Yang shouted.
His body burst forward like a released arrow. The bamboo sword swept horizontally, producing a blazing slash through the air identical to Rengoku's attack.
Rengoku froze where he stood.
The rest of his sentence died in his throat.
That was unquestionably Flame Breathing.
Not only that—it was a flawless execution of the First Form.
When Chiba Yang had been doing push-ups earlier, the breathing method he used clearly wasn't Flame Breathing.
Did he… just learn the Breathing Technique and the First Form simply by watching once?
Even Muichiro Tokito, who became a Hashira in only two months, had not demonstrated talent this terrifying.
A storm of shock surged through Rengoku's mind.
Chiba Yang's talent had reached a level that was almost incomprehensible.
Meanwhile, Chiba Yang frowned slightly.
Something about the technique had felt uncomfortable.
When he used the breathing method just now, it felt restrained, as though he hadn't fully unleashed his lungs. He felt certain that his lungs could expand even more to draw in additional oxygen.
"Rengoku-sensei, was my First Form correct?"
Chiba Yang turned and asked.
Instead of answering immediately, Rengoku walked over and stood beside him.
"Yang," he said.
"You should participate in the upcoming Final Selection."
The demonstration had made one thing absolutely clear to him.
The boy before him was a once-in-a-century genius.
The ordinary rules of the world simply did not apply to him.
What others needed one or two years to learn, this boy could master after watching once.
It was as if the favor of the gods had been poured entirely onto him.
"Huh?"
Chiba Yang blinked in confusion.
"But didn't you say earlier that it was too early for me to participate?"
"My judgment was wrong!" Rengoku declared loudly.
"With your talent and your current mastery of Breathing Techniques, passing the Final Selection will be effortless!"
There was not a trace of jealousy in his eyes—only pride and excitement.
Because he knew something clearly.
The Demon Slayer Corps would soon gain another fighter capable of reaching the level of a Hashira.
For the Corps—and for all humanity in this country—that was a blessing.
"What about your test, Rengoku-sensei?" Chiba Yang asked.
"There is no test anymore!"
Rengoku crossed his arms and laughed loudly.
"Your mastery of breathing is already equal to mine—perhaps even beyond it. I can no longer think of any trial that would be meaningful for you!"
Then he added,
"However, over the next few days you should continue refining your sword techniques. Develop techniques that suit your own breathing style."
"Of course, I will also teach you all the forms of Flame Breathing. I hope you can gain something from them!"
Chiba Yang felt slightly dazed after hearing that.
It almost felt as though he had just become Rengoku's disciple… and was already about to graduate.
"Yes! I will work hard!"
Over the following days, under Rengoku's guidance, Chiba Yang began developing sword techniques suited to his personal breathing style.
With the assistance of the Transparent World, Chiba Yang possessed an unparalleled understanding of his own body. This allowed him to refine techniques at astonishing speed.
At the same time, he also learned all five forms of Flame Breathing, along with its ultimate technique—
Flame Breathing, Ninth Form — Rengoku.
All of this was accomplished in just six days.
On the morning when the Final Selection was about to begin, Chiba Yang stood at the gate of the Demon Slayer Corps headquarters.
Beside him stood Kanao Tsuyuri, who would also be participating in the Final Selection.
At Chiba Yang's waist hung a sword.
It was a spare Nichirin Blade that Rengoku had taken from the Corps' reserve. These blades were typically prepared for those who would participate in the Final Selection.
"Rengoku-sensei, I'm leaving now."
Chiba Yang bowed slightly.
"Yes! I believe you will succeed!"
Rengoku shouted encouragingly.
Standing beside him, Shinobu Kocho gave Kanao a few quiet instructions. As always, Kanao responded only with her gentle smile.
After saying their farewells, Chiba Yang and Kanao set off together toward Mount Fujikasane, where the Final Selection would take place.
Once the two had disappeared into the distance, Shinobu turned to Rengoku with a puzzled expression.
"Rengoku, are you sure it's alright to let that boy participate in the Final Selection already?"
"Even if you started teaching him the moment you met, it's only been about a week."
Shinobu had been deeply shocked when she first heard Rengoku's decision.
However, she trusted his character, so she asked only now.
"No problem at all!"
Rengoku answered confidently.
"That boy is a genius!"
"He already possesses his own Breathing Technique, has developed sword techniques to match it, and has even mastered all the forms of Flame Breathing!"
"...In just seven days."
"Seven days…?"
Shinobu was completely stunned by his words.
She stared toward the road where the two figures had vanished, speechless.
At the same time, inside a small cabin on Mount Sagiri, a red-haired boy finished putting on a blue haori patterned with clouds.
He lifted a fox-shaped warding mask and placed it over his face.
"I'm heading out now, Urokodaki-sensei!"