Tonight was destined to be extremely chaotic.
Whether it was Riezel, the Hashira, or the other members of the Demon Slayer Corps, the moment Muzan sounded the horn for the final battle, they all found themselves transported to the Infinity Castle.
Some ended up together, while others were scattered apart.
Riezel, for example, found himself alone in a different location, completely separated from the others.
Unfortunately, the Hashira also experienced the same fate.
Just as they suppressed their injuries with their breathing techniques and gripped their Nichirin Swords, preparing to resume their attacks on Muzan, they were each transported into different parts of the Infinity Castle.
...
*Thud!*
"Damn you, Kibutsuji Muzan!"
Sanemi pounded the wall in frustration.
...
"Couldn't kill him myself..."
Obanai's face was grim.
...
"So that's Kibutsuji Muzan?"
Mitsuri, after seeing Muzan for the first time, touched her wounds with a lingering fear in her heart.
...
"Even after all the Hashira launched a surprise attack together, we were still crushed in an instant?"
Shinobu furrowed her usually elegant brow.
...
"...Although I hate to admit it, he is just as powerful as Young Tsugikuni said..."
Kyoujurou's face showed no trace of its usual brightness for the first time.
...
"He may be strong, but he's far from flamboyant... What a hideous demon."
Tengen's voice lacked its usual vigor.
...
"I must quickly slay him, or else Master..."
Muichirou, rarely showing urgency, wore a worried expression.
...
"I wonder how Tanjiro is doing now... Is he here too?"
Giyuu worried about his junior.
...
As all the Hashira were separated, each in different corners of the Infinity Castle, cut off from one another, the other members of the Demon Slayer Corps also faced a similar situation.
Fortunately, they had ways to stay connected.
Because they carried their Kasugai Crows with them, the crows had also been transported into the Infinity Castle with them.
"East! East!"
"Head east and regroup!"
"Regroup! Regroup!"
Kasugai Crows appeared in various corners of the Infinity Castle, flying through the air while issuing instructions.
Every member of the Demon Slayer Corps, upon hearing the instructions, immediately sprang into action as if they had found their backbone.
However, as they moved, a large number of demons began to appear within the Infinity Castle.
Moreover, these demons, each transformed into grotesque forms, emerged from unknown corners, roaring furiously as they clashed with the members of the Demon Slayer Corps.
With no choice, they fought back valiantly but soon discovered that these demons possessed astonishing power, nearly rivaling that of Lower Ranks.
"H-How can there be so many powerful demons appearing like this?!"
"Awful! We need to retreat!"
"AAAAAHHHHH—!"
Eventually, they were overwhelmed by the demons, resulting in significant casualties. Even the Hashira encountered these demons, slashing them down one by one, their faces contorted with hatred.
"These demons... they must be the people who suddenly disappeared recently."
"That despicable Kibutsuji Muzan must have given his blood to these people for this moment! Damn it, they are as strong as the Lower Ranks!"
"This is troublesome."
"Ordinary Demon Slayers stand no chance against these demons!"
As time passed, the Hashira began to feel anxious.
The Lower Ranks were already formidable entities just below the Upper Ranks. In the Demon Slayer Corps, being able to defeat a Lower Rank was, after all, considered a requirement for promotion to Hashira.
At this moment, there were only nine Hashira, and aside from them, almost no one stood a chance against the Lower Ranks.
Now, these powerful demons, comparable to the Lower Ranks, had suddenly appeared in great numbers and were besieging every member of the Demon Slayer Corps from all directions. If things went poorly, the entire Corps could be wiped out.
Just the thought of such an outcome made even the likes of Sanemi and Obanai, known for their displeasure with ordinary members, feel restless.
Naturally, all of this was observed by Muzan, who sat on his throne, recovering from his injuries.
"You think I've prepared how many demons for this day?"
Muzan sneered as he watched the spectacle through the demons' eyes.
"For these demons, I've shed more blood than you can imagine. If they can handle it, gaining the power of the Lower Ranks isn't that hard."
Over the past two months, Muzan had the Upper Ranks bring in humans with combat ability or violent tendencies from all corners. He even targeted heavy sin convicts locked away in prisons, all to sift out demons that could serve as excellent forces.
What kind of power would be deemed excellent in Muzan's eyes? Naturally, it had to at least reach the level of the Lower Ranks.
Previously, the Lower Ranks of the Twelve Kizuki were disbanded by Muzan in the cruelest manner possible due to their poor performance. If the demons he sought couldn't even match the previous Lower Ranks, then wasn't all of this becoming pointless?
Because of this, Muzan's method of selecting demon candidates was extremely brutal and straightforward—injecting his blood, which could grant the power of the Lower Ranks, directly into their bodies.
If they could endure it, they would immediately become powerful demons comparable to the Lower Ranks.
If they couldn't endure it, they would explode on the spot.
Through this method, the demons in the Infinity Castle were now, at worst, comparable to the Lower Ranks, or as Riezel put it, roughly equivalent to Level 3.
Demons chosen in this way were naturally beyond what ordinary Demon Slayers could handle.
"In any case, today will be the end of the Demon Slayer Corps."
"From now on, there will be no more Demon Slayer Corps, no more Ubuyashiki."
"Hundreds of years of entanglement has truly sickens me."
"You will all die here."
It was for this reason that Muzan had Nakime transport all members of the Demon Slayer Corps to the Infinity Castle, aiming for their complete annihilation.
Thankfully, the situation was unfolding just as he had imagined.
If this situation continued, soon enough, aside from the Hashira and a few elite members of the Demon Slayer Corps, no one else would survive.
Muzan was confident of this—until those 'things' appeared.
"Wh-What... What is that?"
Suddenly, through his shared vision with the demons in the Infinity Castle, Muzan saw something that made his heart skip a beat and tremble.
He couldn't believe his eyes.
He saw Tsugikuni Yoriichi.
Many of him.
===
"Help! Help!"
A Demon Slayer collapsed on the ground, watching in horror as a demon approached him slowly.
*ROOOAAARRR—!*
As the demon let out a roar, like a wild beast losing its sanity, it pounced.
However, just as the Demon Slayer was about to meet his end at the hands of the demon, a shadow appeared behind the demon.
*Whoosh—!*
With a flash of a sword, the demon's head was severed on the spot and turned to ashes.
"...Eh?"
Muttering this dumbfoundedly, the Demon Slayer, who had been awaiting death in fear, froze.
Before him, a samurai wielding dual swords had silently appeared, swiftly beheaded the demon, and then turned away without even glancing at him.
Before long, he heard cries of demons coming from the direction where the samurai had departed.
Surprisingly, the same scene was unfolding in various corners of the Infinity Castle.
When the members of the Demon Slayer Corps were being unilaterally ravaged by demons whose power rivaled the Lower Ranks, many of these samurai appeared without a word.
They wielded dual swords, expressionless, without communicating with anyone or engaging in banter with demons. It was as if they appeared in this place solely to accomplish one thing—to kill demons.
Clearly, these demons, whose power rivaled the Lower Ranks, could easily ravage ordinary Demon Slayers single-handedly. Yet, they were effortlessly slaughtered by these mysterious samurai.
However, what surprised everyone was that only a few demons managed to survive beyond the first strike.
Thanks to this, every member of the Demon Slayer Corps finally caught a breather, but they were also perplexed as they watched these samurai kill demons effortlessly, unsure of what to make of it.
Especially for those who saw two identical samurai appear before them simultaneously, and others who saw three or four identical samurai fighting demons together, nearly losing their eyeballs in shock.
"What's going on?"
Such a question was on the mind of every member of the Demon Slayer Corps.
"What's going on?!"
Muzan echoed the same sentiment as he yelled.
If Kotetsu or Tanjirou saw these mysterious samurai, they would surely recognize them.
Yes, they were none other than Riezel's combat mechanical dolls—Yoriichi Type One.
Ever since successfully creating Type One, Riezel had spent every spare moment at home creating these mechanical dolls.
In just one month, he had managed to produce hundreds of them—hundreds of mechanical dolls with power rivaling that of the Hashira!
What kind of concept was this?
To put it simply, as the sole Demon Slayer organization in the world, the Demon Slayer Corps had only a few hundred combatants, while the rest were either support personnel without combat ability or lacked the talent to become swordsmen.
As for the Hashira themselves, there were only nine.
Now, however, thanks to Riezel, there were mechanical dolls comparable in number to the entire Demon Slayer Corps, each possessing combat power on par with the Hashira, all mass-produced and deployed on the battlefield.
Without a doubt, this would completely overturn the balance of power between demons and the Demon Slayer Corps, serving as the ultimate trump card that could determine the outcome of the battle.
Meanwhile, swift as a shooting star, Riezel flew through the air, releasing the mechanical dolls from his storage space and deploying them onto the battlefield with a grin on his face.
"I wonder if you'll enjoy this surprise, Muzan..."
If it weren't for the limited number of targets for the magic contract, Riezel would have mustered a true army of thousands of autonomous mechanical dolls to 'serve' Muzan.
Unfortunately, Riezel's control magic compatibility was only second grade, limiting the number of objects he could control independently.
Even so, commanding hundreds of mechanical dolls in battle was a testament to his exceptional 'MAG' and 'Mage' development ability.
Of course, even with these limitations, it was more than enough. At the very least, it would ensure an overwhelming advantage in ground combat.
As for the rest—
"Well, the rest will be left to those Hashira..."
As Riezel murmured to himself, he could feel that it was about time for the Upper Ranks to make their appearance.