Spring passed and autumn came, and a year quickly went by.
Over this past year, Horigaku lived a very fulfilling life on Peach Mountain.
Although the old man, Jigoro Kuwajima, was a bit eccentric in character, he truly knew a great deal. Horigaku learned many skills from this master he'd gotten for free.
Kuwajima was also very satisfied with this disciple he had taken in—diligent, capable, and naturally intelligent.
He cared for Horigaku deeply, imparting all his knowledge without holding anything back.
For the first half of the year, Horigaku primarily focused on tempering his body and practicing swordsmanship.
In the latter half, while continuing to build his physique, he began learning Thunder Breathing.
Thunder Breathing truly lived up to being one of the five foundational breathing styles from the beginning.
Its sword techniques were swift, fierce, and relentless, possessing an unstoppable momentum!
Its power was extraordinary!
After a period of intense training, Horigaku felt that his Thunder Breathing was beginning to take root!
On a certain winter day, Horigaku officially achieved the basics of Thunder Breathing.
There was no particular premonition; it felt as natural as water flowing into a channel.
A sudden intuition told Horigaku that after training for so long, it was time to succeed!
Standing in the snow, Horigaku lowered his stance, bending his knees and settling his center of gravity.
His left hand held the scabbard at his waist, while his right hand gripped the hilt.
He drew a breath of air into his lungs with a mysterious rhythm.
"Thunder Breathing, First Form: Thunderclap and Flash!"
In an instant, arcs of electricity crackled around Horigaku!
He drew his sword!
His entire body transformed into a bolt of lightning, darting forward at high speed!
A cold gleam flashed past!
Horigaku sheathed his blade.
Crack! Thud!
A peach tree as thick as a barrel behind Horigaku was cleanly severed by his strike, collapsing into the snow and sending a flurry of snowflakes into the air.
Hearing the sound of the falling tree behind him, Horigaku smiled with satisfaction. Thunder Breathing was officially mastered! His months of training had not been in vain.
Hm? A killing intent!?
At some point, Jigoro Kuwajima had appeared behind Horigaku.
His eyes glowed red, a dark aura emanating from him like a demon, his tone eerie:
"You brat! Destroying my peach trees again! Die!"
Horigaku immediately took off running!
"Sorry! Sorry! I'm really, really sorry!"
In the snow, one fled madly, the other chased fiercely; the old and the young ran around who knows how many peach trees before finally stopping.
Catching his breath, Horigaku raised a fist in protest at the furious old man Kuwajima:
"Old man! It's just one peach tree! Is it that serious? Peach Mountain lacks many things, but it certainly doesn't lack these things!"
Kuwajima was still fuming:
"You brat, you've been on Peach Mountain for a year now. How many of my peach trees have you destroyed? It's countless!"
"What choice do I have?" Horigaku complained. "There's nothing on Peach Mountain but peach trees. If I don't practice my swordsmanship on them, what should I practice on?"
"More importantly, old man, didn't you even notice? I've officially mastered Thunder Breathing. Instead of praising me, you're giving me a hard time. Tell me, are these peach trees your disciple, or am I!?"
After this outburst from Horigaku, Kuwajima seemed to realize his point and felt a little embarrassed, putting on a profound air:
"Hm? Is that so? You've learned the First Form of Thunder Breathing? Although slower than when I first learned it, your progress is still quite good."
"Old man, are you praising me or insulting me!?"
"Brat, can't you tell? Of course, I'm praising you!"
"Really? I couldn't hear any praise at all!"
And so, their daily bickering began once again.
Having lived together for a long time, Horigaku and Kuwajima understood each other better.
Jigoro Kuwajima was undoubtedly an old man with a childlike heart.
He usually appeared strict and fierce, but he genuinely cared for his disciples, sometimes saying things he didn't quite mean—his personality was quite endearing.
Horigaku's character was a bit irreverent.
He seemed disrespectful to Kuwajima, often arguing with him, but in his heart, he deeply respected the old man.
It was precisely because of this mutual understanding that the old and the young would often stir up commotion almost every day, adding much liveliness to the quiet, cold mountain.
After their usual squabble, Horigaku and Kuwajima gradually calmed down.
Pretending as if nothing had happened, Kuwajima cleared his throat twice:
"Ahem, ahem, well, overall, not bad. You've officially grasped the basics of Thunder Breathing. Keep working hard and continue your training; don't slack off."
"Oh, and after you're done practicing, remember to chop that fallen peach tree into firewood. Leaving it lying around is just an eyesore."
"Got it, old man. You're always nagging endlessly!"
After Kuwajima left, only Horigaku remained in the snowy field.
He gazed at the gloomy sky, at the snowy scenery around him, feeling somewhat melancholy.
This year was the second year of the Taishō era.
It was the year the Kamado family would be slaughtered, the beginning of the tumultuous lives of those siblings, and the start of the Demon Slayer timeline.
During this past year on Peach Mountain, Horigaku hadn't been idle.
In his spare time, he often went down the mountain, searching and inquiring in several nearby towns, asking if there was a family named Kamado living nearby.
Unfortunately, he found no leads.
After repeated disappointments, Horigaku came to understand that the Kamado family was clearly not near Peach Mountain.
Although Japan is an island nation, its territory isn't small, and its population is large.
How could Horigaku possibly have the energy to find a needle in a haystack in just one year? So, the idea of finding the main character was eventually abandoned.
Thus, Horigaku had no way to prevent the tragedy that would befall the Kamado family.
This gloomy weather, this heavy snow, this specific year... it was highly likely that these very days were when the tragedy would strike Tanjiro and his sister.
Shaking his head, Horigaku stopped thinking about things beyond his control.
What mattered was the present, what was for the future, let him from the future deal with it!
What had already happened could not be changed, but the tragedies that had yet to occur—he would stop them.
This was his lifelong goal!
Shifting his mood, Horigaku's fighting spirit reignited. He practiced the Thunder Breathing, First Form, several more times.
As the saying goes, the first step is always the hardest.
After mastering the basics of Thunder Breathing, Horigaku quickly got the hang of the First Form, executing it with increasing proficiency.
Feeling the swiftness and fierceness of Thunder Breathing, Horigaku felt immensely satisfied.
In the original story, the character Kaigaku never managed to learn the First Form of Thunder Breathing, even until his death.
Now, he had learned it. Wasn't this a sign of breaking fate?
Just as Horigaku was thinking this, an electronic sound rang in his mind:
Ding! Detected that the host has broken fate. A butterfly effect has occurred.
System officially activating!
Horigaku was suddenly startled, quickly stopping his sword practice, standing dazed and confused in the snow.
System!?
This is...the golden finger is finally online!?
Damn it! I've been transmigrated for over ten years now!
And you're only coming online now!? Aren't you a bit late!?
Forget it, it's not too late. Strictly speaking, the plot has only just begun.
Feeling somewhat helpless, but more surprised, Horigaku silently asked the system:
"System, explain yourself. What's your deal? What functions do you have?"
The system's electronic voice sounded somewhat monotonous, not very high in intelligence:
Ding! This system's full name is the Butterfly Effect Control System.
Its main purpose is to control the negative butterfly effects caused by the host, while also helping the host become stronger.
Horigaku pondered silently:
"I know what the butterfly effect is, but can it really be controlled?"
Ding! The butterfly effect can indeed be controlled.
If butterfly effects are allowed to run rampant and accumulate, they can lead to terrible catastrophes!
"Alright, you're the system, you're right. What did you just say... control the negative butterfly effects I cause? The butterfly effect has positive and negative aspects?"
"Of course! For example, when the host was a child, unlike in the original story, you were not adopted by Gyomei Himejima, thus not causing Himejima to suffer imprisonment. This was changing fate, triggering a positive butterfly effect."
"Because it was a positive butterfly effect, the system was not activated."
"This time, the host learned the Thunder Breathing, First Form, breaking fate. The triggered butterfly effect is a negative butterfly effect. Therefore, the system activated and officially started!"