Today, the Infinity Castle was especially lively.
Powerful Kizuki, wandering demons outside, and demon servants driven by desire gathered in this twisted place that transcended spatial logic and geographical common sense.
Muzan stood on a suspended terrace.
Today, he lacked his usual refined disguise. Veins bulged on his pale skin. His scarlet vertical pupils burned with a rage enough to incinerate everything.
Akaza's defection, the deaths of Doma and Daki.
This sense of humiliation from losing control was more unbearable to him than physical pain.
"Nakime, is everyone here?" Muzan's voice was low, yet echoed like thunder in every corner of the Infinity Castle.
Nakime, sitting in the shadows, slightly bowed her head. Her slender fingers plucked the strings of her biwa.
Twang—!
With this clear, sharp note, several figures with terrifying auras flashed onto the chaotic steps below the terrace.
"Scary... so scary...."
In the shadow of the steps, an old, grotesque figure cowered at the edge.
He had a forehead covered in wrinkles and bulging lumps. His eyes were completely blood red.
From extreme fear, his teeth chattered uncontrollably.
"Muzan-sama's wrath... it's like thunder, about to shatter my withered bones...."
"It's Doma, that fool... his incompetence has caused lord such distress. This is not my fault...."
"Please don't vent your anger on me...."
He muttered to himself, sneaking glances at Muzan above with his cloudy eyes bearing the Kizuki mark.
His humble, ant-like demeanor completely belied his status as Upper Rank Four.
"Silence, Hantengu."
Muzan's voice was not loud, but it silenced Hantengu like a chicken with its neck grabbed.
"Hehehe, Hantengu-dono is still so timid. What an endlessly amusing comedy."
Another voice came from a porcelain vase nearby.
Upper Rank Five, Gyokko, twisted his deformed, fish-like body, slowly spiraling out from the narrow mouth of the vase.
Where his eye sockets should be, there were no eyeballs, but a pair of constantly writhing mouths. His tone carried a morbid sycophancy: "Compared to that coward, my lord, please take a look at this new lamentation vase I have fired for you!"
"To commemorate the departure of those two colleagues, I collected the finger bones of dozens of artisans as decorations. This luster, these lines...."
"You be silent too, Gyokko." Muzan turned his head. His red vertical pupils contracted and flickered. "I summoned you here not to listen to this meaningless nonsense, nor to have you show off your cheap art."
"Indeed. You should observe your duty as retainers and not be so garrulous."
A heavy, suffocating, murderous voice sounded before the two demons.
It was a swordsman wearing a purple-black checked kimono. His mountain-like pressure made both Hantengu and Gyokko show expressions of fear.
His six eerie compound eyes shifted slightly. Even facing Muzan, his posture maintained the stiff, formal dignity of a Sengoku-era samurai.
He bowed slightly, his voice low like a still, ancient well: "Forgive the wait, my lord."
This was the strongest Kizuki under Muzan, Upper Rank One, Kokushibo.
Kokushibo had peculiar pauses when speaking, stemming from the samurai family etiquette he had retained since the Sengoku period: "To replenish the lost positions, I have brought seeds."
According to Muzan's request, if the Kizuki saw suitable candidates, they could bring them back to the Infinity Castle.
The final battle was imminent. Muzan needed auxiliary fighters.
Kokushibo slightly turned aside. Under the gaze of his six eyes, a young man in Demon Slayer Corps' uniform walked out from the shadows of the pavilion.
The man's face was pale. Cold sweat continuously slid down his temples.
The heavy aura converging from the countless demons in the Infinity Castle had already made it hard for him to breathe.
When facing Kokushibo alone, he could barely hold on. But the moment he stood before Muzan, his originally fragile courage instantly collapsed.
His knees went weak. He heavily fell to his knees on the wooden floor.
"L-lord!" His voice trembled, but his bloodshot eyes shone with a hysterical greed: "I am the inheritor of Thunder Breathing! I am a true genius! Just give me power, and I can be stronger than anyone!"
This man was named Kaigaku, a swordsman from Mount Momo, and Zenitsu's senior disciple.
Kokushibo looked down at the young man at his feet and coldly commented: "Despicable nature, will stop at nothing. The obsession born from jealousy will make him strong."
Muzan looked down at Kaigaku from on high.
"Thunder Breathing? Do you know an ugly woman with blonde hair? She killed my Daki."
"A Thunder Breathing swordsman with blonde hair? Woman... I don't think there's a woman... but there is an ugly man! He's my junior disciple!"
Kaigaku, afraid his answer might displease Muzan, did his best to perfect his response, making it long-winded and verbose.
"Junior disciple? Whatever. Come here."
He extended his hand. Sharp nails abruptly grew from his fingertips. A dense bloody stench erupted in the air.
Kaigaku scrambled forward on his knees a few steps, cupping his hands like a beggar awaiting alms from a god.
"Although you are very weak, I look forward to seeing how those damn Demon Slayers react when they hear about you...."
Muzan didn't intend to let him drink blood. Instead, he directly violently plunged his nails into his forehead.
Demon blood, carrying the power of the curse, roared as it poured into this young man's body.
"Aaaaaahhhh!!!"
Kaigaku let out a scream that nearly tore his throat. His body began to twist unnaturally.
Veins bulged one by one on the surface of his skin. The hazy air currents of Thunder Breathing were, at this moment, dyed into a filthy ink-black.
This transformation continued for some time, until Kaigaku could scream no more and lay barely breathing on the ground.
"From today, you are Upper Rank Six." Muzan withdrew his hand, disgustedly flicking the remaining blood from his fingertips. "In the final battle, I want you to personally tear out the Demon Slayers' entrails."
"Ye... yes, Master!" Kaigaku prostrated himself, responding to Muzan's order with a voice as faint as a thread.
The newly infused blood transformed into black arcs of electricity, leaping between his lips and teeth with each breath.
He felt an unprecedented power. That sense of strength gave his twisted heart ultimate satisfaction.
Seeing this, Hantengu shrunk in the corner and muttered: "Scary.... The newly appointed Upper Six? Young people nowadays are so ambitious...."
Muzan ignored Kaigaku. He turned his gaze to the biwa player sitting higher up, who had remained silent.
"Nakime, your ability to control this Infinity Castle has reached its critical point." Muzan's hand grasped the void, and the entire spatial structure of the Infinity Castle trembled. "I need you to become stronger. Your eyes must cover every shadow of this space. Your will must spread to every corner of this city."
"I want those Demon Slayers to hear your biwa even after they die."
"As you command, my lord." Muzan's tentacles plunged into Nakime's neck. Demon blood flowed continuously through those tentacles.
Her hair began to spread and grow, becoming like vines covering the entire wall, finally revealing a single eye on her face.
Within that single eye, the mark spun and reconfigured at lightning speed, finally settling as… Upper Rank Four.
With a heavy pluck of her fingertips, the Infinity Castle's space expanded at an unprecedented rate.
The original pavilions transformed into an even deeper labyrinth. Countless traps and folded spaces formed in the darkness. The entire city seemed to gain an eerie vitality.
"Next, the reassignment of positions." Muzan looked at Hantengu and Gyokko.
"Hantengu, you will fill Upper Rank Two. I don't want to see you just hiding in the shadows and crying anymore. In the final battle, I want you to go all out."
"Call out Zohakuten. Drag those Hashira all into the abyss of despair!"
"Gyokko, you will fill Upper Rank Three. If your bottles aren't filled with the heads of Hashira, you might as well burn yourself to ash."
The two demons fearfully accepted the order. Although Gyokko was somewhat reluctant to be placed behind Hantengu, under Muzan's captivating gaze, he could only frantically shake his body to show obedience.
"Finally, this one."
Muzan turned his head, looking towards the cold, dark corner deep within the Infinity Castle.
A male demon, wearing samurai clothing and with a strange short spear thrust into his waist, sat quietly on a broken wooden stool.
His face was covered with several layers of yellowed bandages, completely obscuring his eyes. The characters [Mind's Eye] were written on them.
He held a rough cloth in his hand, unhurriedly wiping the thick shield with turtle-shell patterns before him.
Noticing Muzan's gaze, he quickly bowed: "Muzan-sama...."