Muzan: My daughter can't be that weak!

The days passed slowly in Xue Nai's intermittent sleep and wakefulness.

Her periods of lucidity gradually increased, from a few hours to a whole day, and then to two or three consecutive days of clarity.

But after each period of wakefulness, the subsequent deep sleep will be deeper and longer.

Muzan had grown accustomed to her unstable state, and he continued to feed her blood regularly, observing the unique qualities in her that set her apart from other demons.

But he didn't have much patience to delve into it, because something more pressing occupied his mind.

The clues about the blue spider lily remain elusive.

Muzan's patience was wearing thin; he needed a more efficient method and more demons to search for him.

So he came up with the idea of ​​the "Twelve Ghost Months".

He selects the strongest ghosts, bestows upon them more blood, assigns them numbers, and makes them his sharpest blades, enabling them to traverse every inch of land and peruse every book for him.

Meanwhile, ever since Muzan became a demon, the Ubuyashiki family seems to have been cursed.

The men died young, one after another; almost none of them lived past thirty.

In despair, they turned to a family of priests for help and received guidance that the curse could only be lifted by destroying the progenitor of demons, Muzan.

Thus, the Demon Slayer Corps was formed.

When Muzan heard this news, he simply gave a cold laugh.

A human? They actually want to fight against a ghost?

ridiculous.

How could human flesh and blood possibly defeat a monster with regenerative abilities? They were nothing but a ridiculous, desperate struggle.

With that thought in mind, he continued to refine the plan for the Twelve Ghost Months and continued his search for the Blue Spider Lily.

...

On a clear, cool moonlit night.

Ji Guoyan had just finished his mission, but instead of resting immediately, he trained hard on his own.

However, no matter how hard he worked, the figure in his mind remained an inescapable nightmare.

His younger brother, Yoriichi Tsugikuni.

That genius who was born standing on a cloud that he could never reach in his entire life, a genius favored by the gods.

The deeper despair was that he had activated his markings and gained greater power, but at the cost of a clearly visible, short future where he could only live to the age of twenty-five.

Even if he burned away his cursed lifespan, he still couldn't touch Yoriichi's clothes.

Why...?

Disturbed and confused, Yan Sheng picked up his knife and leaped onto the roof, trying to let the night wind blow away the gloom in his heart.

At one end of the roof is a demon with short, slightly curly black hair, dressed in a kimono.

"If that's the case, why not just become a ghost?"

Yan Sheng's pupils contracted, and his hand gripping the knife tensed instantly, his knuckles turning white.

The demon opposite continued, its tone seductive: "By becoming a demon, you can gain unlimited time. You can hone your swordsmanship to its true pinnacle."

"And I want to try turning swordsmen who use breathing techniques into demons."

"How about it? You're different from those ordinary swordsmen; you can choose for yourself."

Yan Sheng's reason told him that he should immediately draw his sword and kill the ghost, but his throat was dry and he couldn't utter a single word.

Infinite time, possibilities beyond limits... these words buzzed in his ears.

In my mind, Yoriichi's calm and serene figure, which seemed to contain the ultimate truth of the universe, reappeared.

The son of God whom he pursued with all his might, yet could not even see his back clearly.

What if... what if I had unlimited time?

Finally, he knelt down.

Yan Sheng's transformation lasted for three days and three nights, and the pain and reshaping he experienced were beyond words.

When everything was over, the one standing before Muzan was no longer the human swordsman Tsugikuni Kokushikatsu.

Muzan looked at him and nodded in satisfaction.

"From today onwards, you are Upper Moon One."

He paused, then said the name:

"Kuroshibo".

Kokushibo knelt on one knee.

"Yes, Lord Muzan."

Having obtained Kokushibo's sharp sword, Muzan's mood did improve briefly.

But the shadow that was about to fall upon him came sooner than he had anticipated.

A few days later, one night, Muzan and Tamayo were walking in the mountains.

Tamayo is a demon he transformed into decades ago; she is very intelligent and also skilled in medicine.

He was pondering the next direction of the search.

Then, he stopped.

In the clearing in the woods ahead, the moonlight poured down without obstruction, illuminating a figure standing quietly.

He was a man wearing a red haori and with his hair tied in a high ponytail. He had long black hair with red ends, and his face was exactly like Kokushibo's, yet he possessed a completely different aura.

Most striking were the sun-shaped earrings he wore.

Muzan's crimson eyes narrowed slightly.

This is the younger brother whom Kokushibo called the son of God.

They arrived so quickly.

It's ridiculous.

There is no god in this world. Only Kokushibo would think that his brother is the son of God. And geniuses are nothing more than flesh and blood.

"I'm no longer interested in swordsmen who use breathing techniques."

Yoriichi seemed somewhat puzzled by his words, but this did not affect his actions.

He drew the sword from his waist.

And he saw it.

The demon in front of me has five brains and seven hearts.

The moment the blade was drawn, Muzan's heart clenched.

It's not because this knife is anything special; it looks quite ordinary.

It's not because of the person wielding the knife, but because of their posture, the rhythm of their breathing, the sense of presence that blends seamlessly with their surroundings…

Danger.

Instinctively, Muzan frantically alerted the police, retreating rapidly without hesitation while unleashing his Blood Demon Art, causing massive fleshy spikes to erupt from the ground in dense clusters.

But Yoriichi had already made his move.

His movements were incredibly fast. Not the kind of speed that relies on brute force like a ghost, but a speed as if he knew the trajectory of everything.

The first strike severed the nearest splinter.

The second strike cleaved through the incoming second wave of attacks.

The third attack was already close to Muzan.

The Nichirin Blade flowed and evolved naturally in his hands.

With this, the thirteen forms of Sun Breathing have been completed.

Muzan's eyes widened as he tried to regenerate flesh spikes to block them, but Yoriichi's sword regenerated faster than he could.

In Yoriichi's hands, that ordinary Nichirin Blade seemed to come alive. Every swing carried a scorching current, severing not only flesh but also the possibility of regeneration.

"you--"

Before Muzan could finish speaking, a blade flashed.

A chill ran down my neck.

His head flew up and spun in the air, where he saw his headless body, Tamayo's shocked face, and Yoriichi calmly sheathing his sword.

Why can't my body regenerate, and why can't my head reconnect to my neck?!

ended?

No. Impossible.

Just before his head hit the ground, Muzan activated a power he had never used in public before, a trump card that even Tamayo was unaware of—his life-saving ability.

"Bang--!"

The enormous explosion shook the surrounding forest.

Muzan's body exploded into many small pieces of flesh, scattering everywhere. Tamayo was thrown back by the blast wave and crashed to the ground, staring at the scene in disbelief.

Yoriichi stood there, calmly looking at the scattered pieces of meat. He had wanted to ask a question, but it was no longer necessary.

The chunks of meat wriggled rapidly after hitting the ground, scattering in all directions.

Yoriichi immediately swung his sword, the blade flashing like a net, slicing through more than 1,500 pieces of flesh. But a small portion, the smallest and most hidden pieces, blended into the shadows and disappeared into the night.

Yoriichi sheathed his sword.

He glanced at the female ghost slumped on the ground in front of him.

"It was so close..."

Tamayo murmured to herself, her voice hoarse, tears finally streaming down her face uncontrollably, "Just a little bit more... He even overcame the weakness in his neck..."

She was emotionally devastated, but in the midst of that devastation, she found herself free from Muzan's control. The curse that bound her vanished with Muzan's explosion.

Tamayo talked to Yoriichi for a long time.

About Muzan, about the blue spider lily, about herself.

She only wanted to watch her child grow up, but in the end, she killed her own child and husband with her own hands.

How could she not hate Muzan? If it weren't for Muzan's deception, she would rather die of illness than live like this.

But she had no way to fight Muzan, so she could only endure it.

She would definitely watch Muzan die, even if she herself would eventually go to hell. Only when Muzan died would she dare to die, and only then would she dare to see her husband and children!

Yoriichi spared Tamayo and asked her to help him kill Muzan.

However, fate often takes a turn for the better.

When his fellow Demon Slayers followed the commotion and found Yoriichi Tsugikuni, they brought even more devastating news:

His elder brother, Kokushikatsu, has unequivocally fallen into demonhood and committed the grave crime of murdering the current lord of the Demon Slayer Corps.

Unable to completely defeat the Demon King, his beloved elder brother turned into a demon and killed the lord, and even let Tamayo escape...

Even someone as strong as Yoriichi Tsugikuni cannot be easily forgiven for this series of derelictions of duty.

Ultimately, burdened by complex gazes and heavy hearts, he was expelled from the Demon Slayer Corps.