What Xiao Yu did not know was that Yoriichi had carved the entire instrument using his newly forged, High Tier 2 Sun-Steel Katana. Using a weapon capable of cleanly severing a boulder to make microscopic, millimeter-perfect acoustic adjustments on fragile bamboo was a terrifying display of absolute blade control.
Yoriichi held the rough bamboo to his lips. He closed his crimson eyes, his mind drifting far away from the Dou Qi Continent, piercing through the veil of reincarnation.
In his previous life, the Demon Slayer Corps had been a place of endless tragedy and blood. But amidst the darkness, there had been fleeting moments of profound beauty.
He remembered a fellow demon slayer—a quiet, scarred man who had lost his entire family—who used to sit on the engawa at night and play a wooden flute. The man had once shown Yoriichi the basic fingerings and breath control required to coax music from the wood.
'Breath is the foundation of the sword,' Yoriichi thought, adjusting his fingers over the freshly carved holes. 'But breath is also the foundation of the soul's voice.'
He inhaled deeply, utilizing a vastly softer, entirely non-combative variation of his Total Concentration Breathing. He directed the steady, unwavering stream of air into the mouthpiece of the bamboo.
A sound emerged.
At first, it was just a low, vibrating hum, testing the acoustic resonance of the hollow bamboo. But as Yoriichi's fingers began to dance across the holes, the hum blossomed into a melody.
It was a beautiful, hauntingly serene tune. It didn't possess the flashy, aggressive energy of a Dou Skill, nor the grand, sweeping pomp of the imperial orchestras that occasionally visited Wu Tan City. It was simple. It sounded like the quiet rustle of autumn leaves, the gentle descent of falling snow, and the warm, melancholy embrace of a setting sun.
Xiao Yu, who had been about to call out to him and ask for a towel, instantly closed her mouth.
The music washed over the clearing, carrying a bizarre, almost physical weight. Because Yoriichi's breathing technique was so profoundly tied to the natural world, the melody inadvertently began to resonate with the ambient worldly energy. Traces of pure, calming Origin-like tranquility laced the sound waves, spreading outward in slow, invisible ripples.
Hearing the melody, Xiao Yu felt an immediate, profound reaction within her own body.
The deep, burning ache in her over-exerted muscles began to rapidly recede. The lingering frustration and exhaustion in her mind evaporated like mist beneath the morning sun. A deep, heavy sense of absolute peace settled over her soul.
She crawled over to the large, smooth boulder she usually used for resting. She leaned her back against the sun-warmed stone, pulling her knees to her chest. She closed her eyes, letting the beautiful, melancholic music wrap around her like a warm blanket.
Within minutes, the brutal toll of the four-hundred-pound training vest claimed its due. Lulled by the hypnotic, restorative melody of her brother's flute, Xiao Yu's breathing slowed, and she drifted into a deep, dreamless, and incredibly peaceful sleep.
Underneath the willow tree, Yoriichi remained entirely in his own world.
His eyes were closed, his posture perfectly relaxed. He felt a deep, swelling sense of fulfillment in his chest. For a man whose entire existence across two lifetimes had been defined by the swinging of a sword and the severing of life, the act of creating something—of producing art and beauty from a simple piece of bamboo—was a profoundly healing experience.
He played the melody again, varying the pitch, exploring the limits of the instrument he had made, his breathing steady and infinite.
However, because both siblings were entirely submerged in their respective states of trance and slumber, neither of them noticed the strange, surreal occurrence that was slowly beginning to unfold at the edges of the clearing.
It started with the birds.
A flock of Twin-Tailed Emerald Finches fluttered down from the upper canopy of the surrounding pines. They did not chirp or sing; they landed silently on the lower branches of the willow tree, their tiny heads tilted, utterly mesmerized by the sound vibrations.
Then came the ground-dwellers.
The thick bushes at the edge of the hot springs rustled softly. Three large, white-furred Mountain Hares—typically incredibly skittish, unranked beasts that fled at the slightest scent of a human—hopped cautiously into the open. They didn't run. They simply hopped a few feet toward the willow tree, then stopped, sitting back on their haunches, their long ears swiveling to catch every note of the flute.
As the midday sun climbed higher, the melody continued, echoing deeper into the dense, untamed forests of the Xiao Clan's back mountains.
The strange, magnetic pull of the music—laced with the profound, pure Dao of Yoriichi's worldly comprehension—acted as an irresistible beacon. To the magical beasts, whose entire existence was governed by instinct and the harsh, violent absorption of raw Dou Qi, the pure, refined tranquility in the sound waves was like an oasis in a blazing desert.
A massive, shadowy figure separated itself from the treeline.
It was a Rank 1 Iron-Hide Boar. Usually highly territorial and aggressive, the massive beast stepped into the clearing with slow, incredibly docile steps. Its heavy hooves barely made a sound on the grass. It completely ignored the sleeping, vulnerable form of Xiao Yu resting by the boulder.
It walked until it was twenty yards away from Yoriichi, then simply lowered its massive, tusked head to the earth, closing its small, beady eyes in apparent bliss.
Time passed. The numbers steadily and silently increased.
A pack of Spirit Wolves, natural predators of the hares and the boar, padded softly into the clearing. The high predators of the outer mountain range did not bare their fangs. They did not growl. They merely walked past their natural prey, their tails lowered in a state of absolute calm, and sat down in a loose semicircle around the willow tree.
The clearing around the hot spring was no longer an empty training ground.
It had transformed into a surreal, impossible tableau. Dozens of magical beasts—predators and prey, herbivores and carnivores, unranked creatures and lethal Rank 1 monsters—were gathered together in absolute, unprecedented harmony.
They did not fight. They did not make a single sound. They simply sat, lay down, or perched in the surrounding trees, forming a massive, silent audience for the lone youth playing a rough bamboo flute beneath the willow tree.
Yoriichi's breathing flowed flawlessly into the wood, completely unaware that his simple pursuit of a past life's memory had just inadvertently demonstrated the legendary, mythical pinnacle of the Beast Taming discipline—subjugating the wild not through force, fear, or spiritual branding, but through the sheer, overpowering purity of a supreme Dao heart.
The music played on, a serene lullaby echoing through a forest filled with sleeping monsters.