"He's trying to get away!" A male Demon Slayer yelled out to inform his comrades, five of them in total had been tasked with eliminating a supposedly surprisingly deadly Demon in the area, and upon finding it the Demon shot them a single glance with one eye and ran off causing the Demon Slayers to follow after him, completely unaware the Demon they were chasing was Lower Moon Two with the name 'Rokuro' and that he was leading them into a trap.
Before the Slayers could realize they had been led to one of many clearings in the forest and from there Rokuro turned around and spread his arms, there was a soft grin on his face that gave off the sensation that the Demon knew he had won, and as for the Slayers, they failed to realize just who they were up against.
As the first Slayer neared the Demon, Rokuro responded, "How nice of you to follow me blindly, Blood Demon Art: Cacophony of Needles!", after the Demon's yell thin yet sharp needles made out of the Demon's cells erupted from his arms, filling the Slayers with holes in a matter of moments before he chuckled to himself and began to relish his catch.
His meal was cut short, extremely short as the faint sound of a Biwa played and Rokuro suddenly found himself in an unknown illogical location, a castle that warped space and time, gravity and location.
His eyes were wide in confusion, the sounds of the Biwa repeated themselves a few times and each time Rokuro found his location in the castle to have changed, before the final strike of the Biwa was heard and Rokuro found himself on a single platform with four other Demons.
He immediately recognized them as Lower Moons just like himself, the lesser members of the Twelve Kizuki.
Before them stood a woman with a certainly rich appearance, the aura of a powerful Demon radiated from her with excessive force, Rokuro didn't know what to think of this, how to process this, before she spoke with a surprisingly masculine voice.
"Lower your heads, and bow."
Every single cell in Rokuro's body forced him to comply and he wasn't alone, all the Lower Moons had bowed facing the woman, no, this wasn't a woman at all, this was Kibutsuji Muzan, their lord.
"M'Lord… My apologies! Your appearance and aura are different, so-" Lower Moon Four, Mukago, began as she tried to appeal to the lord, only to be shushed by Muzan's angered response to her merely talking, snarly her off with a "Who said you could speak?", Makugo remained silent immediately, although shaking in fear as she considered what might happen to her now, "Worms! You may not speak on your own. Only answer my questions!" Muzan continued with a scowl, a short silence befell the castle before Muzan spoke again, "Rui was killed, he was Lower-Five. I want to ask one thing, why are the members of the Lower Ranks so weak?", there was a clear hierarchy in the room, and Muzan dominated it with a presence that demanded fear, respect, and absolute loyalty from his subjects, "Joining the Twelve Kizuki is not the end… Merely the beginning. You must eat more people, get stronger, and become more useful to me. For more than a century, the members of the Upper Ranks of the Twelve Kizuki have not changed. The ones who put the Demon Slayer Hashira in their graves are always the Upper Ranks. But what about the Lower Ranks? How many times have those members changed?"
"What are we supposed to say to that?"Lower Moon Six, Kamanue, thought to the question while digesting the information he had just been given, he was in the right to think that to himself, after all the Lower Ranks could not be compared to the Upper Ranks so it was logical that they'd be the ones to kill the Hashira, but Muzan didn't agree, "'What are we supposed to say to that?' You can answer my question." he said out loud, causing Kamaue to cringe at the realization that Muzan could read their minds whenever he'd feel like it "What has you so worried? Tell me." Muzan demanded.
The Twelve Kizuki, The most powerful Demons under Muzan's direct control and order divided into the Lower and Upper ranks.
Lower Moon Six through Lower Moon One, and Upper Moon Six through Upper Moon One.
Lower Moon Six is the weakest, Upper Moon One is the strongest.
The main way one can distinguish a member of the Twelve Kizuki is the engraving in their eyes, the Upper Ranks have their rank engraved in both eyes while the Lower Ranks have it only engraved in one eye, and the Upper Ranks despise the Lower Ranks.
Kibutsuji Muzan can read the minds of those whom he has given his blood, if he can see them he can read their minds, the further away they are the less he's able to read, but he's always able to discern their exact location, he knows exactly where they are at all times which means… When Tanjiro was taken to the Demon Slayer's Headquarters it was a terrible thing for the Demon Slayers.
Because the moment that Tanjiro arrived Kibutsuji knew the location of Ubuyashiki's headquarters.
However, to this point Kibutsuji has not grasped that Tamayo's and Tanjiro's efforts have removed Kibutsuji's curse, and Kibutsuji still doesn't know it.
"FORGIVE ME, PLEASE LORD KIBUTSUJI!" Lower Moon Six cried out as he was held uphigh by one of Muzan's limbs, one that had morphed into an abominable mass of flesh, muscle, and eyes, "PLEASE, MERCY!"
Muzan already had his plans.
Luckily for Lower Moon Six, they were in his favor.
Muzan dropped the screaming Demon to the ground who quickly recollected their posture and took a bowing stance again, still shaking from the experience.
"Tell me, are you more afraid of the Demon Slayers than me?" Muzan suddenly asked with a monotone voice, his expression had calmed down somewhat although the rage he possesses was still clear, "Every time you meet one of the Hashira of the Demon Slayers, you all wish to flee." he continued, earning a flinch from Lower Moon Four who saw her opportunity for a slight redemption, "No! No, I don't! I'll risk my life for you!" she screamed out through the castle in a mix of pride and fear, "Are you contradicting what I said?" Muzan asked in return, Makugo silenced herself immediately and waited.
"I have decided that the Lower Ranks of the Twelve Kizuki should have another goal. One that I think you will be able to achieve." Muzan began to explain as his eyes scanned the remaining Lower Moons, "You see, there appears to be another Demon on the run that doesn't see me as his lord. A descendant of the man that came so close to killing me centuries ago, your new task will be to find him, incapacitate him, and return him to me. For that purpose I will grant you proper access to the Infinity Castle, aswell as something else." He continued, the Progenitor widened his arms and allowed them to mutate into tendrils of flesh and muscle, creating five total tendrils each adorned with a spiked tip that he used to impale each member of the Lower Moons, and feed them more of his blood.
The Lower Ranks convulsed in utter pain and agony as their bodies were fed power through Muzan's blood, after all was said and done the remaining Lower Moons were writhing on the floor as their bodies adjusted to their new strength and their engravings changed, the images of the boy that was their target flashed into their mind.
The boy's features were clear, yet there were two direct appearances the boy was taking.
One with burgundy hair, deep red irises, and a flame marking on his forehead.
One that looked akin to Rui, white features and red sclera with blue irises.
Yet both appearances had one thing in common, the hanafuda earrings the boy was wearing.
"Rui had failed, I thought that that nuisance had been properly assimilated into his 'family', but I was wrong. He was merely playing a temporary role until he could leave the mountain, therefore I am not even remotely sad about his defeat." Muzan said as a sort of explanation regarding the dualistic appearance of the target Demon, "The one that happens to succeed in your goal will be given more blood." Muzan finally said, followed by the sound of a Biwa that forced all the Lower Moons out of the Infinity Castle.
Each individual member of the Lower Moons digested the information differently but Lower Moon Six, who was now Lower Moon Five, was the first to act, immediately becoming mobile the second he found himself able to in a search for his target.
Bit of a small chapter, but I had nothing else to add to this.
Also yeah, Lower Moons aren't dead.
Also, since none of the Lower Moons aside from Rui actually fought, I'm going to give them Blood Demon Arts myself.