Muzan had not been having an easy time lately, and Oboro was well aware of this.
From reports coming in from all directions, many people had witnessed battles between the Demon Slayer Corps and demons.
These confrontations had been happening frequently over the past few months, and in every single case, the Demon Slayers had emerged victorious.
It was clear that the breathing method was finally beginning to show its true power and effects.
One night, Oboro stood alone in the open courtyard of his residence, moving his limbs and practicing martial arts. As he moved, his mind wandered to the Sun Breathing style that Tanjirō Kamado had developed and refined under his guidance.
The version of Sun Breathing he had taught Tanjirō was modified to avoid harming the human body, yet before Oboro had left the mountains, the Kagura dance Tanjirō had performed had brought about further changes.
It was as if Tanjirō had created these new forms entirely on his own.
This realization led Oboro to an important thought.
Creatures living in this world might be weak, but their intelligence should never be underestimated.
Through the efforts of countless individuals or the influence of shared wills, they were fully capable of developing and expanding upon the basic systems that already existed.
The will carried by the Kamado family, combined with the determination of the Hashira, might very well breathe new life into the breathing method. Doing so would also help him gain a deeper understanding of "inner energy."
The martial arts, training methods, and techniques recommended by the system were all rooted in his memories from his previous life on Earth.
Everything he currently possessed—his skills, his power, his abilities—came from those sources, blended together and refined through his experiences traveling through different worlds.
Yet he had already reached the highest levels of mastery and perfection; advancing further along that path had become extremely difficult.
But did there exist more powerful ways and methods of cultivation?
Of course there were!
On Earth, the breathing method was no longer merely an art of combat—it had evolved into something far deeper, approaching the realm of spiritual cultivation and involving the refinement of the mind and spirit.
However, the system had provided only vague guidelines regarding this aspect, with no clear or specific starting points.
Most of the information came from details he had seen in films, media, and other sources, adapted and transformed by artificial intelligence, based on its knowledge of human anatomy and physiology. In short, what he had access to was essentially an "incomplete version."
It was not easy for Oboro to build upon or advance from this foundation.
To go further, the practice would involve far more than just strengthening the body—it would touch upon the realm of the soul and spirit.
This was something the system could not measure or calculate using data.
Hunter x Hunter, among all the worlds he had visited, could be considered an advanced world, but it was far from the highest level of existence.
If he were to travel to more powerful realms in the future, he would likely find himself completely outmatched with his current level of strength.
Yet Tanjirō Kamado and the Demon Slayer Corps had given Oboro a glimmer of hope.
They also represented one of the most promising aspects of passing down a legacy of will.
Through that shared determination, he might find a way to break through his current limits and advance toward higher levels of mastery.
This might not happen quickly, but over generations, through continuous effort... the power of the breathing method would surely bear fruit. Combined with his own knowledge, experience, and the support of the system, he would grow even stronger.
"This is also what makes a shared legacy different from personal will. A personal will belongs to just one individual, but a legacy represents the efforts of countless people—the combined result of the lives and dedication of many."
After a long moment, Oboro finished his practice, exhaled a deep breath, and spoke softly.
Based on how the system was evolving, further advancements in the breathing method would move beyond the boundaries of ordinary martial arts.
It would begin to resemble what people on Earth called "spiritual cultivation"—something akin to achieving enlightenment or spiritual transcendence.
Of course, based on history from his own world, it was impossible to say whether such things were actually real, since there was no concrete evidence to prove them.
But Oboro was certain that this realm would involve the power of the soul and spirit.
And that would undoubtedly help him elevate and strengthen his own spiritual power.
He had not been able to achieve this on Earth, but now, in this world where the system of power was so rich and varied, it might just be possible for him to reach those legendary heights.
Chiyoko, who had been waiting nearby for a long time, stepped forward as soon as he stopped training and draped his black haori over his shoulders.
"Hmm?"
At that moment, Oboro's eyebrows suddenly lifted, sensing something unusual.
His residence was located in a very peaceful, desirable part of the city, surrounded by beautiful scenery, with hills and streams nearby.
Although it was late at night, he could still hear the sounds of insects chirping and birds calling. But then, all those sounds suddenly stopped—absolute silence fell over everything.
It was a terrifying, deathly quiet.
"Go inside. Do not come out."
Oboro gave his instruction.
Chiyoko nodded, then turned and went back into the house.
"They have finally come to see me..."
Oboro smiled faintly.
He had long expected that Muzan would send demons to approach him. His existence was far beyond anything Muzan had ever considered or anticipated... and he was certain that whoever came would not be Muzan himself.
The demon king did not have the courage to show his face.
"What an unpleasant scent... and such overwhelming aura... Hehe..."
Holding a wooden staff in his hand, Oboro stood alone at the entrance of his residence, waiting for his visitors.
Although he had covered up details about his identity using connections within the Shogunate, it would not have been difficult for either the Ubuyashiki family or Muzan to uncover the truth.
Still, the Shogunate had been very stable recently, with no unrest or trouble breaking out.
That suggested... that Muzan probably held a high-ranking position and status in this era as well.
He had enough influence to reach deep into the heart of the Shogunate's power structure.
"A feudal lord, perhaps?"
Feudal lords were known as daimyō—rulers and governors who held authority over their territories during the Edo period.
Under the rule of the Shogunate, daimyō were ranked and categorized. Some held full independence and autonomy, while others were considered vassal states...
Many were required to send their relatives or children to the Shogunate as hostages, to guarantee their loyalty and obedience.
This system was a double-edged sword, and it often led to the rise of rebel groups and factions.
Whoosh.
A sound so faint it was almost unnoticeable echoed through the air. Perched on top of the gate of the residence, standing beneath the full moon, was a warrior.
He wore a kimono patterned with purple snakes and black markings, paired with black hakama trousers. A sword hung at his waist, and his hair was tied back neatly.
Six blood-red eyes opened and closed on his face, making it nearly impossible for anyone to look directly at him.
If an ordinary person had seen his face, they would have been terrified out of their wits.
This was Michikatsu Tsugikuni—older brother of Yoriichi Tsugikuni, who had lived since the Sengoku period.
Now, he was known as Kokushibō.
Creak.
Oboro looked down again, and saw that the closed gates had been pushed open. Another familiar figure stepped through the entrance, poking his head in first. When he saw Oboro, he immediately broke into a cheerful smile.
"So there you are... I hope I'm not disturbing you?"
"I meant to knock, really... but this Lord moves so fast. To keep up with him, I had to be a little reckless."
"Besides, if I'd waited until after Lord Muzan finished his business, I wouldn't have gotten any credit for coming here."
It was Doma.
Upper Rank Six.
"So early?"
Oboro stared at the eyes in Doma's face, and a thought crossed his mind.
Right now, there was still a long time to go before the end of the Edo period. Gyutaro and Daki had not even been born yet.
"I didn't expect... you would be so polite."
Oboro spoke with a touch of amusement. "You aren't disturbing me... I still have a little while before I go to sleep."
"Did Lord Muzan not come himself?"
"Ah."
Doma looked surprised, then covered his mouth with his hand before his expression turned to one of delighted wonder.
"So you really do know everything... And if I'm not mistaken, you seem... to have become human again?"
"Something like that," Oboro replied, nodding.
"How did you manage that?"
Oboro knew immediately that Muzan had only told his subordinates to find the Blue Spider Lily—he had never explained what the flower actually did or what it was for.
Doma would never dare to underestimate the human standing before him.
They had all heard what had happened to Upper Rank Five, Muryo. And this man had transformed the entire Demon Slayer Corps by himself.
"The Blue Spider Lily, of course... You must have heard of it, haven't you? It is what Lord Muzan has been searching for all this time."
Oboro smiled as he spoke.
The moment he said this, the expressions on both Kokushibō and Doma changed instantly.
They both knew how desperately Muzan wanted the flower. If they could find even a single clue about it, the rewards they would receive would be far greater than simply earning his favor.
"How strange... Even though you already possess such great power, why would you choose to return to being a weak, ordinary human? Don't you think all humans are just empty shells—beings who have no real thoughts, and are only driven by their own desires? I can tell you are different from everyone else... So why would you do something so foolish?"
Doma moved closer, asking his questions with genuine curiosity.
"People have different tastes and ways of looking at the world."
After saying this, Oboro looked at the smile on Doma's face and felt an instinctive sense of dislike. "You remind me of someone... someone I used to hate very much."
That person was Pariston Hill.
Though their personalities and true natures were different, their auras were exactly the kind Oboro could never bring himself to like.
"You hurt my feelings..."
Doma spoke in a soft, sweet, and overly gentle tone.
"Would you... please come with us? Lord Muzan wishes to meet you. Perhaps in the future, we could even become friends... so I would really prefer not to have to fight you. Oh, by the way... do you have any wishes or desires? If you do, you can tell me, and I might be able to grant them for you."
As he spoke, Doma took smaller and smaller steps, moving closer to Oboro.
While Doma was chatting casually, Kokushibō remained completely silent, and made no move to attack. The reason was simple: he was observing Oboro.
Based on everything he had learned, the man before him was no ordinary figure. He had nearly killed Muryo—and had done so with absolute dominance and ease.
Most importantly, Oboro had sensed both him and Doma long before they arrived, and had waited for them deliberately.
Right now, Doma seemed to be just making conversation, but he was actually giving Kokushibō time to assess and evaluate Oboro.
"I welcome you both."
Oboro suddenly raised the wooden staff he held, holding it like a sword as he ran his fingers along its length.
"Especially you... Your arrival has come as quite a surprise to me."
Oboro glanced up at Kokushibō.
"Out of respect, I wanted to show you something first... I think you will find it very interesting."
As he spoke, his breathing changed instantly.
"Lord Muzan has sent you two to me as test subjects... and I am actually quite pleased about that."
A fiery, blazing energy flowed from the corners of his mouth, like flames burning bright.
It was Sun Breathing.
"Come on... Let's have some fun. Don't let this night be so boring."
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