Time flew by quickly during his focused training.
Cheng Mo was immersed in the profound mysteries of Thunder Breathing, forgetting the passage of days and nights.
Cheng Mo slowly sheathed his sword, his chest rising and falling slightly from the intense practice he had just finished, the faint electric sparks lingering around his nose and mouth slowly dissipating.
He stood in place, closing his eyes and looking inward.
The results of several months of arduous training unfolded clearly in his mind like a scroll.
First Form: Thunderclap and Flash had reached the limit his current body could withstand; its activation was like true lightning, and its strike was incredibly powerful.
Second Form: Rice Spirit, a five-strike combo with tricky angles and tight blockade, could now incorporate a slight variation in its thrust.
Third Form: Thunder Swarm, with controllable range and order within chaos, was sufficient to deal with multiple enemies.
Fourth Form: Distant Thunder, a mid-range thrusting strike with a stable trajectory and concentrated power.
Fifth Form: Heat Lightning, he could now consistently imbue his blade with a scorching aura; though not yet at its peak, it had taken initial form.
Sixth Form: Rumble and Flash, relying on his robust physical stamina, he could now simulate the violent momentum of crashing thunder.
Although his proficiency and subtle variations were not yet comparable to the successive Sound Pillars, he could already fluently execute the "form" of all sword styles and initially embody their "intent".
This achievement was enough to astound the world.
Kuwajima Jigorō stood not far away, quietly watching him.
The old man's gaze was complex—relief, pride, emotion… all eventually transformed into an indescribable reverence.
He had dedicated his life to honing Breathing Techniques, and he deeply understood how incredible the level Cheng Mo had reached in just over two months was.
This could no longer be described simply as "genius"; it was almost… a miracle.
Just as Cheng Mo slowly sheathed his sword after a satisfying comprehensive practice, calming the surging Thunder Breathing within him, a faint tremor came from the long-dormant compass illusion deep in his mind, along with a cold stream of information.
[Remaining time until forced departure from current plane: 71:59:59…]
Three days.
Only three days left.
Cheng Mo's hand, gripping the sword, paused slightly.
An indescribable emotion instantly surged into his heart, causing a fierce ripple in his usually calm eyes.
These short three months… no, calculated by the main world's time, perhaps only three days… his experiences in the Demon Slayer World flashed through his mind like a fast-forwarded video.
The exhaustion in the lab, the despair in the hospital, the unexpected compass, the shock of transmigration, life-and-death battles with demons, the transaction at Butterfly Mansion, and the day-in and day-out arduous training on this Peach Mountain… Cheng Mo took a deep breath, suppressing the ripples caused by the compass's prompt.
He thought of his greatest gain from this journey—
The completely mastered supernatural power, and the box of gold sufficient to provide his sister with the best treatment and free his parents from their suffering.
Hope had never felt so real.
A scorching hot current finally broke through his long-frozen emotional defenses, making his fingertips tremble slightly.
He forcibly suppressed the shout that almost escaped his lips, taking a deep breath.
The slightly cool mountain air filled his lungs, but it couldn't quell the wildly beating heart in his chest.
He composed himself, his gaze falling on Kuwajima Jigorō, who was watching him with satisfaction, and on Zenitsu, who was still timid but had something new in his eyes.
It was time to say goodbye.
He walked up to Kuwajima Jigorō.
Without any warning, he solemnly straightened his clothes, then bowed deeply, performing an extremely formal and grand present.
"Teacher Jigorō."
His voice was deeper than usual, carrying an undeniable sincerity.
"For months of guidance and the grace of your teachings, Cheng Mo will never forget; thank you!"
Kuwajima Jigorō was stunned for a moment, then understood.
A hidden dragon must eventually emerge from the abyss; a disciple like this could not be confined to a corner of Peach Mountain forever.
A complex trace of reluctance flashed in the old man's eyes, but more than that was pride.
He accepted the bow, not avoiding it.
Then, he stepped forward and firmly helped Cheng Mo up: "Good child, rise! It is your own talent and effort that have led to today's achievements; this old man… merely did his part."
Cheng Mo straightened up and took out a carefully packaged small pottery jar from his satchel, offering it with both hands.
"Teacher, this is some ointment I prepared based on an ancient family recipe; it has a slight effect in soothing old injuries and calming the mind. Please, you must accept it."
The ointment in the pottery jar was made by him using a base of herbs from this world, secretly mixed with tiny amounts of modern anti-inflammatory, pain-relieving, and mild sedative ingredients.
It was highly safe and indeed effective.
Kuwajima Jigorō took the pottery jar; it felt cool to the touch, and he smelled a delicate herbal fragrance, his heart warming slightly.
He knew this disciple had a reserved temperament, so to be so thoughtful was a sign of deep affection.
He looked at Cheng Mo and patted his shoulder heavily: "Good, you have a kind heart."
Cheng Mo then turned to Zenitsu, who seemed a bit at a loss.
He looked at the golden-haired, timid boy who harbored astonishing thunder within him, and was silent for a moment.
"Zenitsu."
"Yes! Senior Brother!"
Zenitsu stood at attention in fright, stammering his reply.
Cheng Mo looked at him, silent for a moment, then spoke: "Strive to become stronger."
His tone was still calm, but it lacked some of its usual coldness.
"Don't waste… the talent dormant within you, and also…" He paused, his gaze sweeping over Kuwajima Jigorō nearby, "…Grandpa's expectations for you."
This was not direct affirmation, but a subtle acknowledgment.
He pointed out Zenitsu's uniqueness and indirectly affirmed Kuwajima Jigorō's persistent efforts.
Zenitsu froze, his eyes widening slightly, seemingly not expecting Cheng Mo to say such things to him.
He looked at Cheng Mo, then at Grandpa Kuwajima, whose face showed satisfaction, and suddenly his nose stung, and he nodded heavily.
"…Mm! I… I will work hard!"
Although his voice still had a tearful quality, it carried a newfound determination.
Finally, Kuwajima Jigorō looked at Cheng Mo, his expression solemn.
"Cheng Mo," the old man's voice was resonant and deep, "your talent is something this old man has never seen in his life, and perhaps it is unparalleled in this world."
"The stronger the power, the greater the responsibility. This old man asks for nothing else, only that in the future, no matter where you go or what you encounter, you must always adhere to your true self and discern right from wrong."
He raised his hand, pointing towards the distant place where the common people resided down the mountain.
"Use this power for the right path, slay evil demons, and protect the helpless. This… would be the best repayment to this old man."
"May your… path ahead be smooth, with thunder accompanying you."
His words were firm, carrying the heaviest expectations of an old man.
Cheng Mo met Kuwajima Jigorō's gaze and nodded solemnly.
"Teacher's words, this disciple will engrave them in his heart, and will not fail the art taught nor the trust placed in him."
He did not make more promises, but the determination in his eyes said it all.
The setting sun cast long shadows of the three individuals.
The farewell was unspoken.
Cheng Mo turned and walked towards his small hut.
As the time of departure approached, Cheng Mo sent a brief message to headquarters through the "Kakushi" members stationed on Peach Mountain.
The next day, a Kasugai Crow brought a reply: Kagaya Ubuyashiki invited him to his residence for a discussion.
Before leaving, Cheng Mo took one last look at the valley that had hosted his months of arduous training, then resolutely turned and walked down the mountain path.
His back was straight, his steps steady, and he gradually receded into the distance, eventually disappearing into the swirling mist of the mountain road.
On Peach Mountain, only Kuwajima Jigorō's prolonged gaze remained, and Zenitsu's vision was blurred by tears, for the first time not due to training.