Of course, ordinary ropes were no match for demons with extraordinary physical abilities,
so Sarutobi Hiruzen pierced the Four-Armed Demon's collarbones with Konoha's specially made chains and placed numerous Sealing Jutsu on its body.
Along the way, Sarutobi Hiruzen had also kept busy, conducting in-depth experiments and observations on demons as a species.
"After a human turns into a demon..."
"Almost every cell in the body undergoes a complete mutation..."
"Turning into something similar to blood cells..."
"With an almost unlimited ability to regenerate..."
"Just like cancer cells..."
Sarutobi Hiruzen's gaze was deep and penetrating, as though he could see through the Four-Armed Demon before him and examine the structure inside its body.
"So its form is no longer limited to that of a human. Instead, like a tumor, its cells can grow freely in any organ..."
"Of course, the Four-Armed Demon before us can't do that."
"Because the concentration of the progenitor blood inside it—that is, Muzan's blood—is too low..."
"This is about as far as it can go."
"Unless Muzan is willing to give the Four-Armed Demon more of his original blood."
"And the higher the concentration of that original blood inside a demon, the more its cells mutate."
"The stronger its life force becomes."
"Kibutsuji Muzan can even create brains, internal organs, and other body parts at will."
Although demons were far inferior to Ninja in combat strength, their life force and the variety of forms they could take were far beyond what Ninja could achieve.
"Come to think of it, it's rather amusing. This demon can easily achieve what Orochimaru spent his entire life pursuing."
Sarutobi Hiruzen found it fascinating. That was the wonder of a multiverse.
What was unimaginably difficult in one world could be as easy as reaching into a bag in another.
"Still, even setting aside the fatal weakness to sunlight, demons can't truly be immortal."
"At least, judging by the life force of this Four-Armed Demon, it'll only live for a few hundred years before it, too, falls into old age."
At that moment, green Yang Release light from Medical Ninjutsu shone from Sarutobi Hiruzen's hands as he examined the demon's life force.
"Even Kibutsuji Muzan must have a lifespan. Maybe ten thousand years? Or a hundred thousand?"
"Piu."
Suddenly, a sound like a balloon popping rang out, drawing Sarutobi Hiruzen's gaze away from the Four-Armed Demon and toward another table.
A sturdy male corpse lay on it. Of course, he'd still been alive a moment ago.
Now, his heart had burst like a popped balloon.
"Another failure."
There was no shortage of experimental subjects in this chaotic era. It was practically a paradise for human experimentation.
Sarutobi Hiruzen had selected several enthusiastic soldiers who had drawn their swords on him, put them on the operating table, and injected them with demon blood.
Although the experiment had failed, Sarutobi Hiruzen showed no disappointment or surprise.
"As expected, the Four-Armed Demon is still too low-level."
"It hasn't been given the ability to turn humans into demons by Kibutsuji Muzan."
"Muzan may be a bastard, but he's not stupid..."
"He knows better than to drain the pond to catch all the fish. If every demon could spread the infection, and too many demons ate all the humans..."
"Wouldn't Muzan himself starve to death?"
Sarutobi Hiruzen had confirmed a suspicion.
Unless Kibutsuji Muzan allowed it, a demon created through infection couldn't infect anyone else.
"In other words..."
Sarutobi Hiruzen had glimpsed the truth behind the creatures known as demons.
"Demons aren't a species like vampires."
"Or rather, the concept of a demon species doesn't exist."
"Even Kibutsuji Muzan and the other demons aren't in a relationship of parent and offspring."
"Essentially, there's only one collective of demons in the world, and that is Kibutsuji Muzan."
"The other demons are all products of Muzan dividing off some of his original blood."
"That's why Kibutsuji Muzan has such absolute control over the demons under his command."
"He can manipulate their thoughts, restrict their ability to spread the infection, and impose genetic limitations."
Thinking of this, Sarutobi Hiruzen became even more resistant to the idea of becoming a demon.
"No matter how powerful you were as a human..."
"Once you become a demon, you're destined to be enslaved by Kibutsuji Muzan, perhaps even parasitized by him..."
"Not only your life and death, but even your thoughts would no longer belong to you."
Yet even in the world of Demon Slayer, there were exceptions.
A glint flashed in Sarutobi Hiruzen's eyes.
"Unless..."
Suddenly, a clear, slightly youthful female voice came from outside the tent.
"Lord Sarutobi..."
"It's getting dark..."
"We've prepared some food for you."
Sarutobi Hiruzen remembered that the girl was the daughter of the merchant caravan's leader.
"Just leave it at the entrance."
Sarutobi Hiruzen gave the order casually.
"We've also prepared hot water for you..."
"If it's convenient, may I come in and attend to you?"
Hezi's voice sounded again, this time with a hazy hint of flirtation and seduction.
"Then come in."
His steady voice rang out. This time, he accepted Hezi's offer.
By the time Hezi and the servants behind her carried the water and food inside, Sarutobi Hiruzen's tent was completely empty.
The Four-Armed Demon and the test subjects were nowhere to be seen.
"My lord."
Hezi bowed slowly. Beneath her loose kimono, her alluring figure was faintly outlined.
Sarutobi Hiruzen remained composed and spread his arms, signaling for Hezi to help him undress and bathe.
He had agreed to let Hezi in because, ever since entering the world of Demon Slayer, he'd spent the past few days traveling without washing up.
His modern soul found it difficult to tolerate.
Seeing how naturally Sarutobi Hiruzen accepted being waited on, Hezi's eyes shone with admiration, and she became even more certain that Lord Sarutobi was someone of extraordinary status.
And Sarutobi Hiruzen truly was someone of extraordinary status. In the world of Naruto, whether as the head of the Sarutobi Clan or the leader of Konoha, his position had let him live like an upper-class man, waited on by others.
After bathing, Sarutobi Hiruzen began his meal.
Although he had brought plenty of Military Ration Pills, who would eat those when a proper meal was available?
The food before Sarutobi Hiruzen wasn't particularly lavish, but in this small country, he couldn't expect much.
After all, even the Emperor of this little country was only eating salted fish every day.
Behind Sarutobi Hiruzen, Hezi massaged him with just the right amount of pressure.
"Lord Sarutobi..."
"Are you a samurai of the Sanada Clan?"
Hezi was still too young to restrain her curiosity, and couldn't help asking outright.
Sarutobi Hiruzen found it rather amusing.
He had only given them the surname Sarutobi, yet they'd let their imaginations run wild.
Still, there was nothing he could do about it. In this era, even the Daimyo couldn't rival the renown of the Sanada name.
And Sarutobi Sasuke was the top warrior in the Sanada Clan's service. In real history, he was a Ninja of the Koga Clan.
Even Masashi Kishimoto had been influenced by him when he later created the world of Naruto and the character Sarutobi Hiruzen.
So Sarutobi Hiruzen really did have some connection to the Sanada.
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