Thus, under Mitsuba's proposal, with Muzan's additions, and with Michikatsu's observation, that demon organization which would entangle with the Demon Slayer Corps for hundreds of years to come, directly commanded by the Demon King Muzan—the Twelve Kizuki—was born.
The Twelve Kizuki had twelve positions, encompassing the twelve strongest demons in this world besides Muzan himself.
Among them, Upper Rank One was the strongest, and Lower Rank Six was the weakest.
To ensure that the demons ranked among the Twelve Kizuki could always maintain their strength, Muzan specially added a rule called "Blood Battle for Position."
That is, any demon in a lower position could issue a "blood battle" challenge to any demon in a higher position, and the higher-ranked demon could not refuse.
After the blood battle, the victor could devour the loser's blood to further strengthen themselves. If a lower-ranked demon won, they could directly obtain the higher-ranked demon's position.
And Mitsuba and Michikatsu, as the only two powerful demons currently following Muzan, naturally obtained the position of "Upper Rank One" at the top of the Twelve Kizuki.
Originally, Muzan wanted to place Michikatsu and Mitsuba as Upper Rank One and Upper Rank Two respectively, but Mitsuba refused. Her reason was—
"It won't work, Lord Muzan. Don't be fooled by how powerful my Blood Demon Art seems—it's completely ineffective against demons. I can only fight humans.
If you separate me out now, what if some especially powerful demon appears in the future and challenges me? I'll definitely suffer a great loss.
So, it's better to let me share the same position with Elder Brother Michikatsu. This way, if we encounter demons coming to challenge us in the future, it just so happens that I can have my powerful elder brother fight on my behalf..."
To this, Muzan readily agreed.
After all, Mitsuba was stating facts. Her Blood Demon Art was indeed only effective against humans; her actual strength wasn't very powerful. She was the type who excelled in external battles but was poor in internal ones.
If she were really placed in a separate position like this, she could easily die suddenly one day.
That wouldn't do.
Five hundred years—finally encountering a young girl with experiences and personality so similar to his own, who was also loyal, clever, and worry-free. Muzan didn't want Mitsuba to die so early at the hands of other demons.
Thus, Tsugikuni Mitsuba and Tsugikuni Michikatsu, as the strongest demons ever created by the Demon King Muzan, were placed together at the position of Upper Rank One, and for hundreds of years thereafter, this never changed.
Michikatsu was renamed "Kokushibo" by Muzan, while Mitsuba, under Muzan's slightly regretful gaze, declined his intention to also give her a new evil and domineering name.
Among these, because Muzan would always have a stress response to Michikatsu's face, which was extremely similar to Yoriichi's.
He also specially requested, under the pretext of "not being imposing enough," that Michikatsu change his appearance, transforming two additional pairs of eyes on his face.
With these three pairs of eyes, Michikatsu's original appearance was completely obscured.
[Kokushibo?]
Looking at her elder brother who had now become six-eyed, Mitsuba silently complained in her mind.
[Mhm... Lord Muzan's naming sense is really quite poor.]
[Mitsuba, I can hear you...]
"..."
Under the sunlight, the Demon Slayer Corps headquarters was completely silent.
"How could this be..."
After many days, finally returning to the headquarters, intending to report his encounter to Master, Yoriichi saw only devastation everywhere.
Within the headquarters, Demon Hunters' corpses could be seen everywhere. Due to no one collecting them, these exposed corpses in the wilderness had already begun to stink.
Throughout the entire headquarters, the stench of corpses that could trigger human physiological disgust permeated everywhere.
"What exactly happened here... Master... Right! What happened to Master?!"
His pupils contracting sharply, Yoriichi had no time to think further and hurriedly ran toward the mansion where Ubuyashiki lived, located in the valley behind the headquarters.
Behind him, Butterfly and Tamayo, who was holding an umbrella, exchanged glances and quickly caught up to his steps.
The mansion in the valley was equally silent. Walking along the way, corpses of Demon Hunters could be seen everywhere, as if someone had carried out an inhuman massacre here.
"Master?!"
Yoriichi quickly ran into the mansion courtyard. What met his eyes were four corpses lying haphazardly on the ground.
Among these, three were immediately recognized by Yoriichi—they were the Wind Hashira, Sound Hashira, and Water Hashira whom he knew.
And the remaining headless corpse, although its face couldn't be seen, from its clothing, Yoriichi immediately determined its identity.
"Master...?"
His footsteps instantly halted. Looking at Ubuyashiki's headless corpse at his feet in disbelief, Yoriichi stood dumbfounded in place.
What happened?
Who killed Master?
Who exactly did all this?
What demon could have this kind of strength, capable of simultaneously defeating so many Hashira of the Demon Slayer Corps?
Could it be Muzan again?
But hadn't Muzan already been heavily wounded by him? And how did Muzan discover this place?
"It was Tsugikuni Mitsuba."
Behind him, Tamayo, who had closely followed, only glanced at the corpses on the ground and directly spoke the answer that Yoriichi had subconsciously excluded from his mind.
Stepping forward to the dried corpses of the Wind Hashira and Sound Hashira, she said with absolute certainty:
"I've seen her method of devouring humans. She only needs to lightly poke with the flower in her hand, and all the flesh and blood in the entire body will be instantly drained.
What finally remains is this dried appearance exactly like these two corpses before us... I can't be mistaken."
Hearing this, Butterfly stepped forward, very curiously examining these two corpses.
The flesh and blood under the skin were all drained—how exactly was this done...
And Yoriichi only remained silent.
Tamayo didn't stop there. She stepped forward and crouched down, beginning to examine the Water Hashira's corpse nearby.
"Yes, it can't be wrong. It was definitely her."
After a quick and careful inspection, she spoke again:
"This person was missing an arm, but this wasn't the fatal injury that caused his death. His true cause of death was sudden failure of cardiopulmonary function.
If my guess is correct, this person should have suffered an injury in this aspect at some point in the past, and this ultimately became the cause that Tsugikuni Mitsuba used to induce his death, causing him to die suddenly."
After calmly finishing this account, Tamayo stood up and looked at the silent Yoriichi beside her.
"Mr. Yoriichi, this is the terrifying aspect of Tsugikuni Mitsuba's Blood Demon Art.
No matter how distant the past, even if it's just a tiny trigger, she can utilize them and ultimately evolve into the other person's death.
Almost all Demon Hunters, more or less, have suffered some fatal injuries in past battles.
Perhaps in these people's eyes, they have long since healed, but in the eyes of Tsugikuni Mitsuba, who can weave causality, these fatal injuries of theirs have actually always been there, ready at any moment to become killing moves she can utilize.
Demon Hunters... no, I should say humans, absolutely cannot defeat such an opponent.
Even you, I think, would be no exception..."
The courtyard was completely silent. With a quite serious attitude, Tamayo analyzed Mitsuba's Blood Demon Art to Yoriichi.
Power beyond imagination.
Witnessing the scene before his eyes with his own eyes, Yoriichi gave an extremely high evaluation of Mitsuba's Blood Demon Art ability in his heart.
Purely from the perspective of threat to humans, Mitsuba's threat level even exceeded that of the Demon King Muzan.
Arbitrarily modifying causality, controlling fate, deciding your future death from the distant past, even being able to interfere with your thoughts...
Could he really defeat such an enemy?
Yoriichi lowered his head, questioning himself inwardly.
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