I want to evolve the existing power system.
The balance must be shattered, including Muzan, the progenitor of all demons.
Unless Muzan can evolve and bring a higher level of primordial power to this world, his reliance on simple blood transformation will limit him. This fundamental weakness is precisely why Oboro avoided confronting Muzan directly until now.
In the early stages, Oboro only needed to harness Muzan's chaotic influence to create widespread turmoil, making survival more difficult for everyone involved. This forced both the Demon Slayer Corps and its successors to grow through adversity, a crucible of "healthy competition" that forged stronger warriors.
Once Muzan falls, it will signify that the Demon Slayer Corps or his successors have evolved to a new level of power. At that pivotal moment, a successor will rise to claim Muzan's throne and wage war against the Demon Slayer Corps.
The inheritors have always sought to reshape the world, destroying the old to birth something new. This philosophy creates an irreconcilable conflict with the Demon Slayer Corps' mission of protection.
Therefore, peace will never exist in this world. The battle will rage on forever.
As Oboro reasoned, conflicts and contradictions serve as the most potent catalyst for generating power as long as they persist. At the Demon Slayer Corps' current growth rate, Oboro will likely retire long before Tanjiro and the others are born, more than a century from now.
Unless, of course, Muzan surprises him with some new tricks.
After Gyutaro and Daki, siblings, were transformed into demons by Oboro's blood, they absorbed his essence and became true inheritors of his will. That night, amid the falling snow, Gyutaro began his vengeful rampage against the world.
His first act was a massacre.
He systematically slaughtered every bystander who had watched his sister suffer with cruel indifference. Everyone along the Rashomon Riverbank would die by his hand.
Oboro and Chiyoko left before the carnage began; he had no interest in witnessing such brutality firsthand. However, he knew he would need to guide Gyutaro carefully as he grew. Gyutaro possessed far greater potential than Daki, as he would discover in the future. Her existence stemmed purely from their unbreakable sibling bond. To put it bluntly, as Muzan would later observe, the girl was more of a burden than an asset.
Yet, it was precisely this emotional tie that allowed Gyutaro to reach devastating heights of power. Family, lovers, and friends, these emotional connections served as nutrients for the inheritance of will. Separating the siblings was impossible.
What Oboro could do was ensure that Daki wouldn't remain so weak. He planned to teach Gyutaro advanced martial arts, sophisticated combat techniques, and fundamental breathing methods. His breathing techniques transcended conventional limitations; they were universal principles suitable for any living being.
In other words, even demons could master them.
The next morning, news of the massacre sent shockwaves throughout the entire city. The scene resembled hell itself, horrifying every witness. This was the most devastating demon attack in peacetime in recent memory.
Everyone understood that a demon lurked somewhere within the city walls. Over the years, the populace had grown familiar with demonic threats. Soon, Ministry of Justice officials and volunteer demon-hunting teams began systematic searches, but they uncovered nothing, not a single clue.
They could only conclude that the demon had fled the area. The authorities tried to suppress the incident, but complete information control proved impossible. The shogunate, the Demon Slayer Corps, and even the civilian population had become hypersensitive to demonic activity. Word spread to neighboring regions with alarming speed.
Within two days, a Hashira from the Demon Slayer Corps arrived.
This rapid response time reflected the increasingly close relationship between the Demon Slayer Corps and the shogunate. Through governmental channels and political influence, this "war machine" could mobilize with unprecedented efficiency.
Three Hashira came in total.
Given the number of casualties, it was clear that the perpetrator was no ordinary demon. They took this threat very seriously. Oboro had already instructed the shogunate not to interfere, yet the Hashira came anyway. This didn't surprise him.
Faced with absolute conviction, the Demon Slayer Corps would always complete their sacred mission, even if it meant defying authority to eradicate every demon.
However, after extensive investigations, the three Hashira still couldn't locate the hidden demon. They eventually focused their search on Oboro's mansion as the most likely hiding place. Because of his influential status and the heavy security surrounding his residence, the trio had no choice but to remain in the city temporarily, waiting for him to reveal a vulnerability.
"If you want to protect your sister, you must become stronger. From today forward, you'll train under my guidance."
"If you can't accomplish this, what happened to Daki will happen again, and no one will be there to help you next time."
The only person who can save you is yourself."
The Hashira of the Demon Slayer Corps have arrived in this city. With your current strength, any one of them could easily destroy you."
In the moonlit courtyard, Oboro gazed down at Gyutaro, who knelt before him wearing a black haori, and spoke with quiet authority.
After his transformation into a demon, Gyutaro's appearance changed dramatically, becoming identical to his future form. The only difference was the addition of clothing covering his previously bare torso.
Oboro wasn't exaggerating the threat. Under his guidance, this era's Hashira had grown far more formidable than their counterparts in the original timeline. Though Gyutaro possessed immense potential, he had been a demon for only a few days. Furthermore, unlike demons created by Muzan's blood, all of Oboro's inheritors retained their complete human memories. This was possible thanks to the will contained within Oboro's blood, which preserved a crucial fragment of their original consciousness.
"Yes, sir."
Gyutaro's response carried genuine respect and humility. Daki knelt beside him, her body trembling slightly with barely contained emotion.
Given Daki's naturally arrogant personality, it was nearly impossible for her to bow her head in submission to others. When she first encountered Oboro, Gyutaro placed a protective hand on her head, and then they both bowed. Despite knowing that Oboro was their savior, Daki couldn't suppress the cold defiance in her stare. She was convinced that this man didn't deserve such humble treatment from her and her brother.
However, the moment she made eye contact with him, Daki's expression transformed completely. A wave of primal fear and panic surged through her soul, terrifying her and causing her to control her volatile temper. From that moment on, whenever she saw Oboro, Daki couldn't bring herself to look directly at him.
In truth, Oboro had only used a small amount of his soul-based power. Without such discipline, the girl would be impossible to train effectively.
"Let's begin," Oboro said, casting one final cold glance at Daki before dismissing her and addressing Gyutaro.
"Yes, sir."
"Do you sense it?"
"Yes, I do."
"It's definitely there, the aura of demons. There's more than one."
"Should we force our way through? An important figure seems to live in that compound."
Three silhouettes stood atop a building not far from Oboro's residence. Their eyes were focused intently on a shadowed corner in the distance, and they conversed in hushed tones.
"But our lord specifically instructed us before departing that if we encountered this situation, we shouldn't force entry; we should simply withdraw."
One of them recalled their orders with evident concern.
"It seems our lord knows this man's true origins."
"What does that mean? Just because he has powerful connections, does that mean he can harbor demons? Maybe he's already under their control."
At that moment, a short-haired, contemplative man with sharp, calculating eyes suddenly spoke. "Forget it. We're leaving."
"What?"
The other two Hashira stared at him in confusion after this unexpected declaration.
"Yuta,"
The man, the current Water Hashira, took a deep breath before explaining. "My teacher once told me that, many years ago, a Water Hashira from a previous generation encountered something significant in this area. Afterward, he warned every successor he trained that, no matter how serious, if anything unusual or demon-related occurred in this vicinity, they should exercise extreme caution. He specifically emphasized one location within the city, right there."
Yuta gazed toward the shadowed walls in the distance, his brow furrowing with concern. "That senior warned that, even with Demon Slayer Marks activated, individual strength would be useless. We must wait until all Hashira evolve beyond the Marks for a second time, uniting the full strength of the Demon Slayer Corps. Only then would we have the slightest hope of victory."
"Ever since that senior's passing, every generation of Water Hashira has carried this ominous warning."