Speedrun Infinity Castle

"I have located the position of the Infinity Castle; it exists in a different dimension of time and space relative to this world."

"It is Nakime's ability that connects to that dimensional fortress... currently, the high-level demons known as the Upper Moons are all stationed within the Infinity Castle."

"Sora, you cannot kill this guy, otherwise Nakime will die as well."

Shisui's efficiency was remarkable; not only did he realize this was not the Ninja World, but he also glimpsed Uchiha Sora's previous arrival through the memories of Kibutsuji Muzan.

Although Shisui desperately wanted to kill this vile demon who had caused countless tragedies, he knew Sora wanted the Infinity Castle and stated this point in advance.

"Hmm... I know."

"Control him first, have Nakime open the Infinity Castle, and let's go inspect the goods."

Uchiha Sora glanced back at the members of the Demon Slayer Corps and said indifferently, "Do nothing unnecessary; just stand there and watch."

Hum—

The sound of a biwa string suddenly rang out, and a square void appeared beneath the feet of Uchiha Sora and Shisui.

Uchiha Sora grabbed Kibutsuji Muzan by the hair, and the three of them plummeted downward together.

"Ah... there are quite a lot of those things; let's start by recruiting the weaker ones."

Back in the Ninja World, Uchiha Sora had already devised a plan for how to utilize the demons of the Infinity Castle.

Including Kibutsuji Muzan, he intended to pack up and take every single demon with him.

It wasn't that he expected these demons to help him with anything.

Compared to his and Shisui's ocular power, Kibutsuji Muzan showed zero resistance, yet he could at least be considered a Special Jonin.

Then there were those demons like the string-users, who in his memory were about on par with Chunin...

Demons that couldn't be killed were perfect for training Uchiha cubs.

Setting up levels for them to grind experience, allowing them to take on missions once they reached a certain level—it would be just like a rookie training camp.

The Infinity Castle could also serve as a safeguard for all members of the Uchiha clan.

Unless they were killed instantly, hiding in the Infinity Castle would ensure their survival, effectively giving everyone a permanent Reverse Summoning Technique.

Stronger Uchihas could even learn Izanagi to achieve multiple layers of life insurance.

Uchiha Sora's philosophy was to protect the clansmen who did not wish to fight, and for those who were willing to fight, to do his best to ensure they didn't die in vain.

--

Kaigaku Inadome, the newly appointed Upper Moon Six.

He was once a swordsman of the Demon Slayer Corps, but after encountering the Upper Moon One, Kokushibo, during a mission, he turned into a demon to survive.

His evil was not triggered by a desire to live; even in his youth, he had extinguished the incense burners that warded off demons, leading to the deaths of his companions.

His instincts as a demon told him that the one being dragged like a dead dog was the source of all demons, the Demon King, Kibutsuji Muzan!

Without the slightest hesitation, he threw away his sword and knelt to beg for mercy.

"Two lords, I am..."

Slash—

A scorching blade of light sliced him in two, and in an instant, he turned into ash.

"This one won't do; he's too weak."

Uchiha Sora commented indifferently.

Compared to ordinary demons, this Upper Moon official was slightly stronger, but as a mini-boss for a level, he was far from qualified.

As for Nakime, she didn't need an interview; she was already an internal hire.

Uchiha Sora had made this entire trip specifically for her sake.

Using Kibutsuji Muzan as a conduit, Shisui ordered Nakime to teleport the Upper Moon Three to this location.

Just like the previous demon, Akaza saw Kibutsuji Muzan the moment he arrived.

Though his mind was shaken, he did not display the unsightly behavior of his predecessor.

He assumed a fighting stance.

"Is that so... that's great..."

"I can feel your strength just by looking at you; if I could be killed by you, that would be a fine ending!"

Uchiha Sora slowly raised his hand.

"Sorry, I can't grant your wish."

"I've arranged a job for you with no days off."

BOOM!!!

The chakra, heavy as if it had physical substance, crushed Akaza until he was pressed flat against the ground!

Chakra-Pressure.

After experimenting with this method of using chakra on Uchiha Itachi, Uchiha Sora had fallen in love with the sensation.

Shisui glanced at him, clicking his tongue in secret.

Even though using ninjutsu would be more chakra-efficient, such wastefulness...

But it really was cool; it's great to have so much chakra.

I need to step up my training too...

"Next."

Doma, Upper Rank Two.

With rainbow-colored irises and hair the color of white oak, he looked quite noble and beautiful.

He lacked the joys, angers, sorrows, and pleasures of a normal person, nor did he feel fear.

Even upon seeing the miserable state of Muzan, he merely covered his face with his fan and chuckled.

"Yo-ho-ho, a powerhouse I've never seen before—did you take care of the incredible Lord Muzan~?"

He glanced at Akaza, who was being suppressed by the chakra, and his smile widened: "How rare to see you being so sensible, Lord Akaza."

Turning his head to look at Uchiha Sora, Doma chuckled softly: "I can submit too, you know. I don't mind doing anything."

"Because... you are so beautiful~"

"Just like a bright red spider lily growing in a volcanic crater, that kind of beauty that lures people toward death."

"To be able to continue working with Lord Akaza, I am also quite moved—"

His voice came to an abrupt halt.

Doma looked at the flames igniting on his body and asked with a hint of confusion: "Why is that? I should be stronger than Lord Akaza, shouldn't I?"

"Ah, I just dislike the tone of your voice. That's all."

"I... don't quite understand."

"You don't need to understand."

Uchiha Sora formed a seal with one hand, and the scorching flames burned Doma to nothing, leaving only ash behind.

Akaza, who had been struggling with all his might, relaxed slightly.

"Next."

Upper Rank One, Kokushibo.

Originally named Tsugikuni Michikatsu, he was the brother of Tsugikuni Yoriichi, the man who had left Muzan severely wounded.

Due to jealousy of his brother's talent and fear of the curse that claimed the lives of marked swordsmen at age twenty-five, he chose to join the side of the demons.

Muzan held him in high regard, not treating him as a subordinate to be ordered around, but rather as a partner.

His strength could be considered equal to the sum of all other Upper Ranks combined!

Clang!

Muzan being captured did not cause him to lose his fighting spirit; the moment he saw Uchiha Sora and the other, he drew his blade.

"Can you not see the gap in our strength?" Uchiha Sora said indifferently.

Kokushibo gripped his sword with both hands, his voice low and measured: "To face a powerhouse such as yourself without drawing my blade would be a discourtesy."

Uchiha Sora's eyes lit up.

He drew Ryuzuki, the blade overflowing with deep red patterns, looking magnificent.

All six of Kokushibo's eyes trembled in unison.

After Uchiha Sora drew his blade, he clearly saw the shadow of that man...

As scorching as the sun, an existence he could never reach!

--

--

There was no way to see the trajectory of the blade.

Even the sensation of being cut only reached his brain several seconds later.

Clang--

Uchiha Sora sheathed his blade and said indifferently behind Kokushibo, "Compared to that trash Muzan, at least you still have ambition."

"I will take you to a new world; if you can manage it, reaching an even higher realm is not impossible."

Squelch—

Blood sprayed into the air, and the blade forged from Kokushibo's own flesh fell into the pool of blood, severed in half.

"From today on, your master is me."