HxH: I Will Be Supreme

"Are you leaving?"

The question hung in the mountain air like morning mist, heavy with unspoken meaning. A few days had passed since Oboro's decision crystallized in his mind, and now he found himself climbing the familiar paths of Mount Kumotori one last time.

The elderly Tanjiro Kamado sat on the wooden porch of his family home, his weathered hands wrapped around a steaming cup of tea. Beside him stood a small boy with bright, curious eyes-Tanjuro, Tanjiro's son, who would one day father the protagonist of the world's greatest story.

If Oboro stayed here another twenty years, he might witness the birth of this legendary demon slayer, along with all the other key figures who would shape the destiny of this reality. But the truth was undeniable: the Demon Slayer's world had changed so dramatically under his influence that the original plot could never unfold as intended.

The Kamado Clan remained a bloodline of destiny, but their ultimate enemy might no longer be Muzan. It could just as easily be Doma with his ice-cold perfection, Kokushibo with his centuries of refined swordsmanship, Gyutaro with his unrelenting fury, or any of the scattered heirs who had gained power beyond their original scope.

The outcome depended entirely on who emerged victorious from the coming storm.

If Muzan somehow triumphed over all his enemies, perhaps young Tanjiro's fate wouldn't stray too far from the original timeline. After all, Oboro had promised the Demon King that victory would bring him the ultimate reward - true immortality, immunity to sunlight, and power beyond the limitations of his current form. Combined with the widespread knowledge of soul power techniques, the Demon Slayer Corps would face challenges beyond anything they had previously imagined.

But regardless of who would ultimately emerge victorious, the fate of the Kamado Clan would be shaped by the power that dominated the demonic hierarchy. The players had changed, but the game itself would continue.

More importantly, the very nature of this world had been revolutionized. Demon transformation had become easier than ever, their numbers had multiplied exponentially, and soul power techniques were spreading throughout both the human and demon populations. The future held endless conflicts between factions and individuals vying for supremacy.

Through all these changes, the Demon Slayer's world had successfully evolved into a higher reality. Oboro's mission was complete.

Even among the higher worlds, this one would rank in the lowest sequence - but its elevation represented a monumental achievement. The metaphorical tree of the will of this world had grown tall and strong, its branches reaching out to new possibilities.

The Will itself seemed remarkably pleased with these developments.

Oboro's cooperation with the ruling will of this world had served several purposes. First, it eliminated the risk of being targeted as a dimensional threat, allowing him to operate freely without interference. Second, it gave him complete access to everything this reality had to offer, allowing him to carry out his plans without restriction.

He even suspected that the groundbreaking discoveries of the Kamado clan-the development of qi points and circulation techniques-had been subtly influenced by the Will of the World itself. The tree's growing power had manifested as inspiration and insight for those most dedicated to advancing breathing techniques.

Most importantly, his next dimensional crossing would carry significantly reduced risk factors. When he finally passed through the space-time barriers that separated realities, the enhanced protection would help him avoid being caught in temporal rifts or dangerous turbulence.

Mutual benefit had been the basis of their cooperation.

"Yes," Oboro nodded, accepting the cup of tea Tanjiro offered with steady hands.

"Will you ever come back?" the older man asked, though his tone suggested that he already knew the answer.

Something deep in Tanjiro's soul recognized the finality of this moment. The man sitting across from him radiated a sense of completion, as if every thread connecting him to this world was being carefully cut away. Logically, nothing in this reality should pose a threat to someone of Oboro's caliber, yet the feeling of permanent departure was unmistakable.

Oboro shook his head slowly, the gesture carrying the weight of absolute certainty.

Young Tanjuro watched the conversation between his grandfather and the mysterious visitor with quiet fascination, sensing the significance of the moment without fully understanding its meaning. Old Tanjuro had never revealed Oboro's true identity to his descendants - in their minds, he was simply a dear friend who visited occasionally with gifts and stories.

This discretion had been at Oboro's own request. His goals in this world had been achieved, which meant that the Kamado Clan would no longer have to bear the burden of their connection to him. The cause and effect that had bound them together for generations would end here and now.

In Oboro's eyes, he had always been a visitor from faraway shores, never truly a part of this reality. His interference had been necessary but temporary - a disturbance that would eventually stabilize into something greater.

The deeper truth was more complicated. The reason previous generations of the Kamado Clan had been able to sense his presence in their dreams and memories was because Oboro had deliberately altered Tanjiro Kamado's soul when they first met. This mental manipulation had been intended to cultivate the "seed" of the breathing techniques over several generations.

The act hadn't been malicious, but it had certainly been selfish. He hadn't expected or intended to harm the boy, but he hadn't put the child's well-being above his own goals.

Future generations - Tanjuro and his eventual son - would not inherit this supernatural link. Only the lineage of Yoriichi Tsugikuni, the original master of Sun Breathing, would remain in their bloodline.

"Where will you go?" Tanjiro asked, his voice heavy with complex emotions he could not quite articulate.

"Home," Oboro replied simply.

The single word carried layers of meaning that none of his companions could fully comprehend. After wandering between dimensions for what seemed like a lifetime, the concept of "home" had become both more precious and more elusive than ever.

An hour later, their last conversation came to an end. Oboro rose from his seat and walked slowly down the mountain path, carrying a small map that contained everything he needed for the next phase of his journey. Behind him, the Kamado family watched until his figure disappeared between the trees.

But before he left, he had shared one last truth with the elder Tanjiro.

"The child's feelings for me were the purest I've ever encountered," Oboro had said, his voice unusually soft. "No ulterior motives, no complex thoughts - just genuine kindness and friendship. When I first came to Mount Kumotori in the Edo period, my intention was to use the Kamado family. Not only him, but you as well."

"This is who I really am."

After hearing these words, Tanjiro finally understood which ancestor Oboro was referring to. A name had emerged from the depths of his inherited memories: Tanjiro Kamado, the boy who had once felt the warmth of Oboro's hand ruffling his hair in those ancient flashbacks.

At that moment, Tanjiro desperately wanted to call out to the departing figure, to offer some words of comfort or understanding. But something stopped him.

The concept of being "used" did not bother him as much as Oboro seemed to expect. The Kamado clan possessed a remarkable intuition when it came to reading people's hearts, and both ancestors who had interacted with Oboro would have sensed his hidden motives from the beginning. Even Tanjiro himself could sense the layers of calculation beneath Oboro's outward kindness.

Yet, despite knowing they were being manipulated, the Kamado family had chosen to welcome this mysterious man into their lives. This willingness spoke volumes about the bond that had formed between them.

The improved Sun Breathing techniques had indeed saved the Kamado clan from generations of suffering and early death. But more than that, the memories passed down through their bloodline carried genuine warmth and affection. The happiness young Tanjiro had felt in Oboro's presence could not be manufactured or faked - it lived on in her soul as pure, unadulterated emotion.

No matter what schemes Oboro might have pursued in later years, that original bond remained real and precious.

After processing these revelations, Tanjiro found himself unable to call out to the departing figure. Suddenly, he understood why Oboro had chosen to share this painful truth with him.

The Kamado clan's unconditional acceptance and genuine friendship had become a source of discomfort for someone accustomed to viewing all relationships through the lens of utility and manipulation. Their simple, honest affection was exactly what made Oboro uncomfortable with his own actions.

Tanjiro felt the same. He knew that Oboro had come with ulterior motives, but that knowledge did not diminish his respect and care for the man.

"Now I understand why our ancestor liked you so much," Tanjuro murmured with a gentle smile.

Young Tanjuro, who had been watching Oboro's retreating figure with the innocent perception that only children had, suddenly spoke up. "Grandfather, he seems lonely. Doesn't he have a family?"

Tanjiro reached down and ruffled the boy's hair, his expression becoming thoughtful. "Of course he does. He's just temporarily lost his way. I think he'll be back with his family soon."

The words carried more hope than certainty, but sometimes hope is all that remains when saying goodbye to someone who has shaped your world in ways both wonderful and terrible.

Several days later, as midnight approached in a desolate area of Ueno, the newly assembled Twelve Demon Moons gathered at the appointed meeting place.

Muzan had not yet arrived.

When the demons reached the designated place, they discovered that someone had beaten them there. Kokushibo sat in the center of the open room, his posture perfectly straight in traditional samurai style. His six eyes reflected the moonlight as he methodically polished his blade, the ritualistic movements as precise and unhurried as a meditation.

He did not acknowledge their arrival or show surprise at their presence.

The assembled Twelve Demon Moons tensed visibly, their expressions growing grave as they recognized the legendary figure before them. Over the years, Kokushibo had systematically eliminated countless upper- and lower-level demons. His reputation for ruthless efficiency had become the stuff of nightmares even among their own kind.

What bothered her most was his complete lack of reaction to her appearance. Shouldn't he at least appear surprised or alert? How could he remain so calm in the face of so many enemies?

The Demons had been ordered by Muzan to surround and eliminate Kokushibo, but they'd only been given minimal information about their target. Muzan had deliberately withheld the full truth about this mission, leaving them unprepared for what they were about to face.

Judging by Kokushibo's demeanor, he'd known about their coming long before they'd set foot in this place.

"This is really your style, Muzan," Kokushibo said quietly, his voice carrying the weight of centuries as he slowly sheathed his polished blade.

He could see through the deception at once. The Twelve Demon Moons were used as expendable weapons, sent to test his strength while their master watched from a safe distance. After all these years, Muzan's basic character remained the same - he trusted no one completely and viewed every subordinate as a disposable tool.

Somewhere in the shadows beyond the moonlit clearing, the real battle was about to begin. But first, Kokushibo would have to deal with these pawns sent to die in the service of their cowardly king's paranoia.

The night air grew heavy with anticipation as both sides prepared for violence. This confrontation would determine not only who lived and who died, but which vision of the demonic world's future would ultimately prevail.

And in the darkness beyond, other forces were stirring - forces that would soon converge on this battlefield to settle scores that had been building for over a century.

The final act of Oboro's grand design was about to unfold.