Chapter 28: Encountering the Ghost Dance at Tsuji Muzan

For the past six months, Rengoku Masachika had either stood before the memorial tablet of his deceased wife, Komaki, or drunk alone in the inner chamber.

Each time Rengoku Senichirou prepared a meal, he would go call his father to eat.

After finishing all the household chores, he would go alone to the backyard and continue swinging his wooden sword.

But Rengoku Senichirou did not know that whenever he trained alone, Rengoku Masachika would always watch him from a corner.

After more than half a year of reflection, Rengoku Masachika now finally awakened.

After his wife’s death, he had sunk into self-destruction—drinking to numb himself, abandoning himself, fleeing reality!

He had betrayed his wife’s hopes, disappointed his children, and nearly tarnished the Rengoku family’s name.

Even seeing him in this state, Rengoku Kyōjirou and Rengoku Senichirou had never once considered giving up on him—they had always looked up to him.

Even as he became this, they always found ways to help him rise again.

They had always believed their father would one day recover and resume teaching them as he once had.

After watching Rengoku Senichirou practice for a while, he returned to Rengoku Ruka’s room, stared at the memorial tablet, and fell into deep thought.

“Ruka… perhaps I truly must change…”

He cast one final glance at Rengoku Ruka’s memorial tablet, then rose and left the room…

The next day.

Zero returned to the Demon Slayer Corps headquarters and received a message from his Kibakō.

“Master, the Fujiyama Trials! The Fujiyama Trials!”

Only then did Zero remember that besides being a Pillar of the Demon Slayer Corps, he was also an examiner for the Fujiyama Trials.

To avoid forgetting, he had instructed his Kibakō, Snow, to remind him when the time came.

Calculating the time, he had been with the Demon Slayer Corps for nearly a year, and the Fujiyama Trials occurred once annually—now was the right moment.

“Snow, how many days until the trials begin?”

“Five days! Five days!”

“Understood.”

“Looks like I won’t be able to attend this Pillar Meeting—I’ll have to ask Xiao Yue to attend for me.” Zero thought, then shouldered his scythe and hurried toward his residence.

On the way, he encountered the Butterfly sisters.

“Oh? Zero, you’re back~”

“Hmm, Kanae, Shinobu, what are you two doing?” Zero asked, seeing both sisters holding Nichirin blades, as if preparing for something.

“Shinobu has been at the A-Class rank for a long time, and I’m taking her on a mission right after this. Once this mission is done, she’ll be ready to advance to Pillar rank and join me at the Pillar Meeting in five days!”

“I see. Congratulations, Shinobu—you’re about to become a Pillar! Amazing!” Zero sincerely congratulated her.

Over the past year, Shinobu had either been researching poisons at Butterfly House or accompanying Kanae on missions, slaying numerous demons.

When Zero first met the Butterfly sisters, Shinobu was still a B-Class swordsman.

Half a year ago, she had already advanced to A-Class.

Now, counting the time, she had nearly slain fifty demons.

By the time the Pillar Meeting ended and he returned, Shinobu would likely already be a Pillar.

“Of course! I won’t hold my sister back!” Shinobu replied with a proud pout.

“Zero, will you attend the Pillar Meeting?”

“I won’t be able to—I’m the examiner for the Fujiyama Trials and must prepare. I’ll ask my sister Xiao Yue to attend for me.”

“I see…” Kanae seemed slightly disappointed, but quickly adjusted her mood.

“Then, Zero, we’ll see you later—I’ll take Shinobu on her mission now!”

“Hmm.”

Kanae watched Zero’s retreating figure, lost in thought, not even hearing her sister call her.

“Sister!”

“Huh? What is it, Shinobu?”

“Sister, what’s wrong? I’ve been calling you for ages!”

“Nothing. Let’s go—get ready, we’re leaving soon!”

“Oh~”

Though curious, Shinobu still obeyed Kanae, though her thoughts were elsewhere.

Watching Zero’s departing figure, then glancing at her sister, she thought: “Could it be… that Sister…”

…

“I’m back, Xiao Yue!”

“Master!”

Xiao Yue, seeing her master, flew straight into Zero’s arms and clung to his chest.

Zero, amused and exasperated, lifted her into his hands and said, “Alright, alright—you’re not a child anymore.”

“Hehe~”

“Xiao Yue, in five days I’m leaving for Fujiyama to supervise the trials. You’ll attend the Pillar Meeting for me. I’ll lift your [Growth Function]. When it’s over, I’ll take you out again.”

“Mm-hmm, no problem!”

Over the past year, to ease Xiao Yue’s worries, Zero returned every one or two months to take her out for walks and sightseeing.

Xiao Yue never complained; she was always delighted on these outings, knowing her master kept his promise to her.

…

Five days later.

Before departing, Zero left Xiao Yue two hundred [Energy Crystals] and lifted her [Growth Function], then arrived early at the Demon Slayer Corps perimeter.

Ubuyashiki Hikaru, Ubuyashiki Hikari, and the ten high-rank swordsmen had already been waiting.

Zero then retrieved the [Nano-Alloy Armored Vehicle] from his [Nanospace] and led them toward Fujiyama.

After about seven or eight hours of travel, Zero drove the armored vehicle to the foot of Fujiyama.

After disembarking, Zero returned the vehicle to his [Nanospace], took Ubuyashiki Hikaru and Ubuyashiki Hikari by the hand, and climbed the stone steps, the ten high-rank swordsmen following behind in two lines.

Upon arrival, he found five or six trial candidates already waiting—some were repeat applicants who had failed previously.

Since the trials began at night, Zero stood on the high platform, with Ubuyashiki Hikaru and Ubuyashiki Hikari flanking him, and the ten high-rank swordsmen lined up behind him in two rows.

The trial candidates, seeing Zero again and this imposing lineup, were inevitably startled.

…

Butterfly House backyard, Pillar Meeting.

After absorbing the energy from the [Energy Crystals], Xiao Yue transformed into a child of about 1.2 meters tall, then changed into a beautiful halter dress—one of the gifts Zero had brought her on past visits.

Xiao Yue—child form

A red-and-white dress, black flat shoes, a cherry blossom hairpin adorning her head.

Her blue hair hung loosely, her large, bright blue eyes giving her the appearance of a cheerful, sunny little girl from next door.

After preparing, she arrived early at the Butterfly House backyard to wait for the others.

First to arrive were the Butterfly sisters and Mitsuri Kanroji, laughing and chatting as they entered the backyard.

But when they saw a tiny, adorable girl standing there, they were stunned—Mitsuri’s eyes sparkled with stars.

“Wow! So cute! Hey hey, what’s your name? I feel like I’ve seen you before!” Mitsuri asked, leaning in.

Even the Butterfly sisters felt the same—something about her seemed familiar.

Since Zero was the only one who had seen Xiao Yue after lifting her [Growth Function], they had no idea this child was Xiao Yue.

“Kanae, Shinobu, Mitsuri, don’t you recognize me? I’m Xiao Yue.”

“Huh!?” The three women exclaimed in unison.

But upon reflection, it made sense—only Xiao Yue called them by those nicknames.

“How did you grow up?” Shinobu asked.

“My brother used a special method to temporarily enlarge me. When the time’s up, I’ll shrink back to normal.”

Zero had already instructed Xiao Yue on how to explain this, so the three understood.

Zero had previously said that due to special circumstances, he had shrunk Xiao Yue—so now being able to enlarge her was no surprise.

Still, this was their first time seeing Xiao Yue enlarged—they gathered around her, peering, poking, pinching her cheeks.

Soon after, Tomioka Giyuu and Shinobu Muichirou arrived. Muichirou stood silently beside the yard, staring at the sky.

Giyuu stood alone on the other side, expressionless as always.

Shinobu Muichirou: What shape is that white cloud up there?

Tomioka Giyuu: I’m different from them.

Then came Uzui Tengen, striding in with a flamboyant gait. Seeing Xiao Yue, he clucked in admiration: “Oh! Who’s this splendid little sister? So dazzling and adorable! Hahaha! How about becoming my splendid adopted son?”

“Sure—if you can beat my brother, I’ll consider it! Hehe~” Xiao Yue said, smiling with the same sly, cunning grin as Zero.

“Your brother is?”

“You know my brother—he’s Zero!”

Uzui’s eyes instantly turned into dots—he recognized the name instantly. But he didn’t understand why Xiao Yue had grown so large.

He remembered her as tiny, small enough to fit in his palm like a wooden doll.

But the thought of fighting Zero made him shudder—not just because he doubted he could win, but because Zero’s weapons alone could turn him into a sieve with a single one.

Especially after seeing Zero fight Yuki no Tsubasa—those machine guns, that strange metal box firing missiles—he’d be dead before he even reached Zero…

“Uh… that’s not at all splendid!”

“Puff~” The three women barely held back their laughter.

Time passed second by second.

Kyōjurō Rengoku, Shinobu Kocho, Muichiro Tokito, and finally Shinobu’s brother, Mitsuri Kanroji, all arrived at the back courtyard of Butterfly House at that moment.

They were curious to see Xiao Yue; Mitsuri, though blind, could sense her presence.

It was Butterfly Kanae who explained everything, and only then did they understand what had happened.

While everyone waited for Ubuyashiki Kagaya’s arrival, another unexpected person appeared.

This man wore the same flame-patterned haori as Kyōjurō Rengoku, the Demon Slayer Corps uniform, and carried a Nichirin Blade nearly identical to Kyōjurō’s.

His eyebrows were sharp like swords, his hair the color of flame.

He was the former Flame Hashira—Kyōjurō Rengoku’s father, Kyōjurō Rengoku.

“Father!” Kyōjurō Rengoku, seeing his father arrive, was undoubtedly the happiest among them.

Kyōjurō Rengoku approached his son, placed a hand on his shoulder, and said: “Rengoku, I’m sorry. It was my fault—I disgraced the Rengoku name, betrayed your mother, and caused you and Senjuro worry.”

Hearing these words, Kyōjurō Rengoku suppressed the urge to cry; he could feel it—his father had changed. The old Kyōjurō Rengoku had returned.

“Father, welcome back!” Kyōjurō Rengoku shouted with fiery enthusiasm.

Then Kyōjurō Rengoku turned to the other Hashira beside him and bowed deeply in apology: “I apologize, all of you. It was my fault. I beg your forgiveness.”

After his wife’s death, Kyōjurō Rengoku fell into despair, stepped down from the Flame Hashira position, and drowned his sorrows in alcohol.

Some of them had visited him before, tried to comfort him—including Ubuyashiki Kagaya himself.

But all were mercilessly driven out by Kyōjurō Rengoku; he was furious inside—his beloved wife was gone, and how could they possibly understand his pain!?

But since that one conversation over drinks with Zero, he had spent the past six months in self-reflection, and finally understood.

Every single person who joined the Demon Slayer Corps had lost family, loved ones, or endured even greater suffering!

They joined not only to kill demons and avenge their lost loved ones, but to protect.

He had felt this pain, this bitterness, this despair—and yet, hadn’t others felt the same?

“Welcome back, Kyōjurō-san!” Butterfly Kanae spoke first.

“Welcome back!”

“Kyōjurō-san, welcome back!”…

The others followed suit, expressing their welcome; they were glad Kyōjurō Rengoku had emerged from his shadow and returned to the Demon Slayer Corps.

Seeing that no one blamed him, Kyōjurō Rengoku’s tears welled up, and he felt a warmth in his heart.

“Forgive me for embarrassing you all—I’m old, and I cry easily.” He quickly wiped his tears.

Just as everyone was rejoicing, two girls’ voices came from the inner chamber.

“Lord Ubuyashiki has arrived!”

Ubuyashiki Hina and Ubuyashiki Kanao cried out together.

“Good morning, my swordsmen children!”

All the Hashira, including the retired former Flame Hashira, knelt halfway to show respect.

Xiao Yue did not kneel like them, but no one objected—they all knew Zero did the same, so it was natural for his sister to act likewise.

Ubuyashiki Kagaya stepped before them, looked up at the sky, and said: “What a fine day—the sky is still so blue!”

Everyone looked up and saw that Ubuyashiki Kagaya’s curse had vanished completely; his complexion was rosy, no longer the frail, weak figure he once was.

Muichiro Tokito: “Lord Ubuyashiki, your health?”

“Thank you, Tokito. Zero has completely lifted the curse from my body. Now I can do more for all of you!”

He then turned to Kyōjurō Rengoku: “Kyōjurō-san, I am truly glad you’ve returned. Thank you for choosing to rejoin the Demon Slayer Corps.”

“Lord Ubuyashiki, you overstate it. It was my fault that I caused you all such distress. I am no longer the Flame Hashira—my son, Kyōjurō Rengoku, shall inherit the position. But I will return to train and teach the other swordsmen!”

“That is excellent. Thank you, Kyōjurō-san!”

Then Ubuyashiki Kagaya sat cross-legged on the tatami in the inner chamber, with Ubuyashiki Hina and Ubuyashiki Kanao kneeling respectfully behind him, one on each side.

Everyone rose to their feet and began today’s meeting.

“Let us begin today’s Hashira meeting.”

“Lord Ubuyashiki, one person is still absent!” Shinobu Kocho said.

The person referred to was Zero.

“My apologies—it was my oversight. I assigned Zero as examiner at the Demon Slayer Corps’ Final Selection at Mount Fujikasane to recruit new blood, so he cannot attend this meeting. His sister, Xiao Yue, will represent him for the remainder of the proceedings.”

As soon as he finished speaking, all eyes turned sharply to the childlike Xiao Yue.

“That is correct. When my brother returns, I will relay the meeting’s contents to him.”

After Xiao Yue and Ubuyashiki Kagaya explained the situation, everyone understood and stopped asking questions.

“Today’s meeting concerns one matter: I wish for Butterfly Shinobu to become the Eleventh Hashira of the Demon Slayer Corps. Please voice any opinions.”

“I—I agree!” Mitsuri Kanroji spoke up first.

“I agree too!” Shinobu Kocho followed immediately.

“Mm, I agree!”…

In the end, everyone—including the retired Flame Hashira Kyōjurō Rengoku and Xiao Yue, representing Zero—agreed without objection.

Originally, there could only be nine Hashira, but since Zero’s proposal at the last Hashira meeting, everyone had changed their minds.

Rules are rigid, but people are flexible—some rules can indeed be changed.

Moreover, Ubuyashiki Kagaya approved this decision.

“Then, Shinobu, have you chosen your title?”

“My Lord Ubuyashiki, my Breathing Style is derived from my sister’s Flower Breathing—it is Insect Breathing. I shall use ‘Insect’ as my title.”

“Very well. I hereby declare that from this day forward, Butterfly Shinobu shall be the Eleventh Hashira: the Insect Hashira!”

“Yes!”

The rest of the meeting focused on the Demon Slayer Corps’ future plans and discussions of demon attacks in various regions; it lasted until nightfall…

The sun set behind Mount Riluoxi; night descended.

At this moment, around thirty swordsmen had gathered at Mount Fujikasane for the selection, half of whom were former candidates who had failed before and were reapplying.

Yet many others who had failed previously did not return—likely because they felt their strength was too weak and needed more training, or for other reasons.

Ubuyashiki Hina and Ubuyashiki Kanao: “To all swordsmen, thank you sincerely for enduring hardship to join the Demon Slayer Corps’ Final Selection today!”…

Ubuyashiki Hina and Ubuyashiki Kanao delivered the same speech as before; finally, it was Zero’s turn.

After explaining the rules, the candidates gradually entered Mount Fujikasane, including those reapplying who stepped back into the mountain once more.

But among them, Zero noticed a very strange man—a man with a sullen expression, eyes that looked down on everyone.

As this man passed Zero, he froze upon seeing Zero’s crimson eyes and quickly stepped aside.

As he walked away, he muttered under his breath: “How can a Hashira have eyes like that? What a damned bastard!”

Though whispered, Zero heard it clearly—and he had also seen in that man’s gaze arrogance, selfishness, utter disdain, and contempt.

But Zero paid it no further mind; his duty now was to supervise the candidates.

“Proceed exactly as last time. Remember—do not intervene unless absolutely necessary!”

“Yes, Zero Hashira!” Ten high-rank swordsmen shouted in unison, then split up, beginning their duties as they had in the previous selection.

Zero then retrieved twenty “Destroyer Mini-Drones” from his Nanospace, switched their high-explosive rounds for paralysis rounds, and used his “Analytical Glasses” to control their dispersion.

He activated the projection, displaying all drone-captured footage onto a screen floating in midair.

He also remembered one other thing: that mysterious green arm. He felt certain it belonged to a mutated demon within Mount Fujikasane.

Though he had sent multiple high-rank swordsmen to investigate before, they found nothing.

So this time, he resolved to observe carefully—and he sent his Sound Hashira, Snow, into the mountain as well.

…

Time passed slowly; the seventh day of the selection had reached dawn.

In these days, around twenty candidates had been eliminated, mostly first-time applicants; only a few were those who had failed previously and failed again.

Zero’s gaze remained fixed on the twenty video feeds from the drones, yet still found no trace of the green-arm demon.

“Strange—no sign at all!? Either I misjudged last time, or this mutated demon is extremely cautious.”

After much thought, Zero leaned toward the second hypothesis—he trusted his own perception. That green, alien arm was undoubtedly from a mutated demon within Mount Fujikasane.

Gradually, the sky lightened with the first pale glow of dawn; the sun rose in the east. Zero still saw no trace of the green-arm demon, yet he remained certain he had not been mistaken.

It only meant the mutated demon was exceptionally vigilant—hence, it had remained hidden.

He decided to stop overthinking and recalled his drones.

But in a dark corner of Mount Fujikasane, the green arm, as soon as the strange flying objects vanished into the sky, swiftly extended, seized a demon about to flee from the sunlight, and retracted.

Soon, a sound of chewing echoed.

Zero watched the remaining fewer than ten candidates and frowned slightly, though, comparatively, this selection was better than the last.

Most of them were former candidates who had returned to reapply.

What followed were the closing remarks, the selection of Sound Hashira, and the choosing of Nichirin Blades.

When the ceremony ended, Snow flew back from Mount Fujikasane to report.

“Snow, did you find anything unusual?”

“Master, no anomalies detected. Everything remains as before.”

“I see… Thank you, Snow.”

Not finding anything did not mean Zero abandoned his suspicion—he still firmly believed a mutated, alien demon existed within Mount Fujikasane.

Then Zero gathered the remaining Nichirin Blades, took Ubuyashiki Hina and Ubuyashiki Kanao by the hand, and led the ten high-rank swordsmen down to the mountain’s base.

Retrieve the [Dark Alloy Armored Vehicle] and return everyone to the Demon Slayer Corps headquarters.

After several hours of travel, Zero delivered everyone to the Demon Slayer Corps, then returned the two Ubuyashiki children to the Ubuyashiki residence before returning to his own estate.

At the estate, Zero listened as Xiao Yue reported the contents of the Pillar Meeting.

“Master, these are the minutes from the recent Pillar Gathering.”

“I see. Shinobu has been promoted to Pillar rank—congratulations! Thank you, Xiao Yue. Tonight I’ll patrol my region first; in a few days, I’ll take you out again.”

“Mm-hmm! Thank you, Master! Mwah~” Xiao Yue’s heart leapt at the thought of another outing with Zero; she flew before him and kissed him on the cheek.

“You! What am I supposed to do with you? Who taught you this? I’m going to bathe—go look after Snow. She’s probably exhausted after all these days.”

“Yes, okay~”

……

“It’s been a year already. I wonder how Zero-brother is doing?” Tanjiro walked down the street, carrying a bamboo basket filled with charcoal, remembering the time he and his family spent with Zero.

“Ah!!! Tanjiro, help me!” A young man, blood dripping from his nose and his face bruised, shouted at Tanjiro as the shopkeeper’s wife held him fast.

The villagers at the foot of the mountain all knew Tanjiro, for he was kind-hearted and often helped them.

“Tanjiro, they’re accusing me of breaking the dishes! Please help me!!” The young man thrust a cloth bundle containing broken pottery before Tanjiro.

Tanjiro sniffed it with his nose and said: “There’s cat scent on this.”

“Oh! It’s a cat!” The shopkeeper’s wife finally realized her mistake.

The young man immediately broke free and cried: “I told you! It wasn’t me!”……

Night fell, snow swirling heavily.

After selling all his charcoal, Tanjiro found it was already dark; he walked along a forest path, hurrying home.

“It’s so late—I must get home fast! But at least I sold all the charcoal today! And with the money Zero-brother gave me still left over, I can buy plenty of treats for my siblings!”

Thinking of this, Tanjiro quickened his pace.

But as he passed a house, an old man called out to him.

“Hey, Tanjiro! Still planning to go back into the mountains? It’s dangerous after dark! Stay here tonight!”

“Grandpa Sanro, it’s fine—I’ve got a sharp nose!”

“Stay at my place tonight, it’s nothing! Come on!”

“But…”

“Enough! There are demons out there at night!”

Thus, Tanjiro stayed at Grandpa Sanro’s house, persuaded by his advice.

Yet Tanjiro did not know that, because of this, he narrowly escaped disaster!

On Yunxue Mountain.

A man in a suit and Western hat walked through the snow—he was Kibutsuji Muzan.

Suddenly, he sensed human presence nearby and conceived a plan.

“Well then, since I have nothing better to do, let me see if I can create a subordinate immune to sunlight.”

With that, he walked toward the source of the human aura…

At the Kamado home, Nezuko had just soothed Rokuta to sleep and turned to her mother: “Mother, Brother hasn’t come home yet—is something wrong?”

“Don’t worry, Nezuko. It’s late—I’m sure Grandpa Sanro made Tanjiro stay over. The mountains are dangerous after dark.”

“I see…”

“Go rest now, Nezuko. Don’t fret—Tanjiro will be back tomorrow.”

“Yes, I understand.”

“Yukio, Shigeru, Hanako—go to bed now! Stop playing!”

“Yes, Mother.”

As Nezuko prepared to carry Rokuta to rest, she saw someone approaching outside the window and thought it was Tanjiro returning.

She rushed to open the door—when a powerful force shattered the wooden door; a whip lashed across Nezuko’s body, and Rokuta, in her arms, was struck and collapsed unconscious.

“Nezuko! Rokuta!” Kotohira Kamado snapped to attention and lunged forward to shield them, but tripped over shards of the broken door and fell to the ground.

A metallic crystal fell from her grasp.

It was precisely because of this fall that Kotohira avoided Muzan’s next whip strike.

“Sister! Mother!” Yukio, Shigeru, and Hanako rushed to help—but Kotohira shouted: “Children, stay where you are! Yukio, protect them!”

She immediately snatched up the metallic crystal, recalled Zero’s words, and charged back to Nezuko and Rokuta!

She shielded them beneath her body.

“How tedious,” Kibutsuji Muzan sneered, his eyes full of contempt, and swung the whip again!

In that instant, Kotohira pressed the button on the metallic crystal—a spherical blue light erupted, blocking Muzan’s whip and protecting her, Nezuko, and Rokuta.

“Hm? What is this?! It blocked my attack?!” Muzan stared in disbelief at the blue spherical shield, momentarily stunned.

Seizing the moment, Kotohira grabbed Nezuko and Rokuta and rushed to join Yukio and the others, clutching the metallic crystal tightly.

“Hmph! Even so, let’s see how long this strange thing can protect you!”

He resumed lashing the whip at the spherical shield.

Each strike sent violent tremors through the barrier; Kotohira clung to her children, watching Nezuko’s grievous wounds and Rokuta’s unconscious form, and finally broke down, tears streaming down her face.

“Someone—please save my children!” Kotohira prayed desperately.

Muzan realized the strange blue shield, though strong, dimmed slightly with each of his attacks.

“I see… heh. Let’s see how long you can hold out.”

His method worked: after several minutes of continuous strikes, the shield’s glow began to fade.

As he prepared to intensify his assault, a deafening cannon blast echoed from behind him!

Boom!

Muzan instantly dodged aside.

But the bullet was faster—he was struck through the shoulder, exploding and shattering it.

Only when he regained his bearings did he recognize the figure before him.

“So it’s you.”

……

[Beep! Beep! Beep! Beep! Beep! Beep!]

Zero had just finished patrolling his region and was preparing to return to the Demon Slayer Corps headquarters when his [Analytical Glasses] suddenly blared a violent red alert!

[ALERT! ALERT! DANGER!]

“Huh? What’s this?!” Zero immediately activated his [Analytical Glasses] and saw the signal: his [Quantum Shield] had been attacked.

He had given the [Quantum Shield] to Kotohira Kamado; uneasy, he had linked it to his [Analytical Glasses], so he’d receive immediate alerts if extreme danger arose.

Seeing the red alert, Zero realized the Kamado family was in mortal peril.

He retrieved the [Photonic Flyer] from his [Nanospace], inserted an energy crystal, and strapped it to his back.

The [Photonic Flyer] unfolded its black-and-white metallic wings and shot toward Yunxue Mountain.

“I have to make it in time!”

The [Quantum Shield]’s danger alert filled Zero with dread—he suspected only a Upper Moon-level demon, or perhaps… the Demon King—Kibutsuji Muzan—could inflict such damage.

But whichever it was, he wouldn’t let it go. A meal and a night’s shelter from the Kamados—this debt demanded repayment.

Such a kind family must not suffer.

“Maybe Kanae was right—I really have changed…” Zero thought.

After several minutes of flight, he arrived above the Kamado home on Yunxue Mountain.

But when he saw the strange figure before him—his right arm transformed into a long whip, striking the [Quantum Shield]—Zero didn’t hesitate. He pulled out the [Dark Alloy Annihilation Cannon Sniper].

He unleashed “Concentrated Detonation,” firing straight at the figure.

Boom!

The deafening cannon blast echoed through the forest; the strange man failed to dodge in time—his shoulder exploded.

Zero landed before Kotohira and the others, aiming his sniper cannon at the figure, and activated his [Analytical Glasses] to scan the data.

[Name: Kibutsuji Muzan]

[……]

“What?! This guy is Kibutsuji Muzan?!” Zero’s mind reeled.

The moment he saw the first data from the [Analytical Glasses], he understood everything—there was no time to read further, for Muzan had already regenerated.

“So it’s you,” Kibutsuji Muzan fixed his gaze on Zero.

He had learned of this demon slayer from Upper Moon Five—he recognized Zero as a Pillar of the Demon Slayer Corps.

Zero’s immediate priority wasn’t further analysis—he needed to protect the Kamados while finding a way to defeat Muzan.

His power was suppressed by this world’s boundaries to roughly half its strength; from Muzan, he sensed real danger.

Moreover, the [Quantum Shield] could withstand only three or four more strikes before its energy depleted—then the Kamados would be defenseless.

Around Zero, space rippled—dozens of [Dark Alloy Cross Floating Cannons] materialized, forming a protective barrier before him.

On his way here, Zero had preloaded each Cross Floating Cannon with several [Energy Crystals] as a precaution—and now they proved useful.

Muzan stared at this strange technique, baffled: how had he done it?

He himself could do it—but only with Muzan’s Blood Technique, and only within the Infinite Castle.

“I know you. You’re the one who killed Upper Moon Five.”

“And what if I am?”

"Heh, you were supposed to die—but if you’re willing to accept my blood and become my subordinate, I’ll overlook what happened before!"

"Moreover, I can make you the strongest Upper Moon—even let you take the seat of Upper One!"

"Heh..."

Seeing Zero laugh, Muzan Kibutsuji suppressed his fury: "What are you laughing at?! Become a demon, and you’ll gain endless life and grow stronger! And if you help me find the Blue Higanbana, I’ll become the perfect ultimate being—then you too can..."

"Shut your mouth! You’re a pitiful little brat!"

"What did you say?!!!"

"I said you’re a LITTLE BRAT!! You’re not even half my age, and you dare talk to me like that? You’re pathetic!"

"Impossible! You damned human! How can any human live this long?!"

"Believe it or not, it’s your choice—die!"

Boom!

The railgun fired another bullet, spinning at extreme speed toward Muzan Kibutsuji’s abdomen—where one of his brains resided.

During his exchange with Muzan, Zero had scanned his body structure, seeking weaknesses.

To his surprise, the [Analytical Glasses] revealed Muzan Kibutsuji had five heads and seven hearts.

A plan instantly formed in his mind: what if he destroyed one of Muzan’s brains or hearts—would it weaken him?

But to his shock, the brain struck by the railgun regenerated instantly.

"Incredible regeneration speed," Zero thought.

Swish!

Ding!

Muzan’s whip struck with blinding speed—but was blocked by Zero’s Cross Floating Cannons, unable to close in.

Zero fired at Muzan Kibutsuji while rapidly calculating a counterstrategy.

He also had to dodge Muzan’s attacks—he remembered what Yuze had told him: Muzan’s attacks carried his blood.

His earlier suspicion—that Muzan’s blood contained poison and curses—had been confirmed.

Thus, every strike was executed with extreme caution.

Yet the longer the battle dragged on, the more stunned Zero became—not only because Muzan had broken the sound barrier in his attacks, but because his regeneration was astonishingly fast, completing in an instant!

Even targeting his hearts and brains, regeneration occurred in the blink of an eye.

Soon, he understood why.

Because his [Dark Alloy Annihilation Railgun] couldn’t use [Energy Crystals], it couldn’t produce an effect like the Nichirin Blade.

Although "Concentrated Detonation" could severely damage Muzan Kibutsuji, it required two full seconds to charge!

Yet Muzan Kibutsuji was equally stunned.

He realized every one of his attacks was blocked by those strange black-metal crosses—his whip’s speed was extraordinary.

"Damn this bastard! What kind of weapons are these? How can they have such defense?!"

Swish! Swish!

Muzan’s other arm transformed into a whip and lashed out—again, the Cross Floating Cannons blocked it.

But this strike was powerful enough to knock one of the Cross Floating Cannons flying.

Shu!

"Shit!"

In the instant one [Dark Alloy Cross Floating Cannon] was knocked away, Muzan’s whip lashed forward—Zero had no time to dodge, so he blocked it with his mechanical left arm.

Boom!

The impact hurled Zero backward several meters; a faint white mark remained on his mechanical left arm.

The surface was coated in blood—Muzan had clearly tried to pierce his skin and inject his blood, turning Zero into a demon.

Since the mechanical arm blocked it, the blood only clung to the surface.

"Zero!"

"Zero-niisan!"

Kamado Kie and her children shouted from behind him.

"Stay where you are! I’ll protect you!" Zero shouted to them, shielded within the [Quantum Shield].

"Looks like I need close-range combat—I’ll have to use that weapon," Zero thought.

He retracted his [Dark Alloy Annihilation Railgun] into the [Nanospace].

"Dark Alloy Armor—arm!"