Lower Ranks Meeting

The Lower Ranks meeting was a gathering and massacre that immediately followed the death of Rui, Lower Five of the Twelve Kizuki. It occurred in the Infinity Castle and covered Muzan Kibutsuji's lack of faith in the Lower Ranks and his subsequent decision to kill them all.

Prologue
The Twelve Kizuki is an organization consisting of the twelve most powerful demons who serve directly under the Demon King Muzan Kibutsuji. Split into 6 member rankings, they consisted of the Upper Ranks and the Lower Ranks. The Upper Ranks of the Twelve Kizuki remained unchanging for nearly 113 years, with no single member dying to the Demon Slayer Corps; as further credence to their strength, only the Upper Ranks have been successful at killing members of the Hashira. In stark contrast, the Lower Ranks would continue to lose and change members in that same time, shifting positions and possessing an inconsistent and lacking strength that disappointed Muzan.

Eventually, the death of Rui, a powerful and favoured member of the Lower Ranks, at the hands of the Demon Slayer Corps would drive Muzan to deem the echelon as a whole to be entirely useless to him. He subsequently ordered the Biwa Demon Nakime, owner and manipulator of the Infinity Castle, to summon each of the five remaining members.

Meeting
The Lower Ranks are summoned to the castle in numerical order. Enmu, Lower One, is taken to the castle first, followed by Lower Two Rokuro, Lower Three Wakuraba, Lower Four Mukago, and finally, Lower Six Kamanue. Enmu calmly walks about the castle, while his peers stay still in worried anticipation. Kamanue, being the lowest and weakest member, becomes confused the moment he was summoned, having never seen the Infinity Castle before and (correctly) assuming the Biwa Demon in the castle's centre is the owner of the space. He sees Enmu and Rokuro in the distance and notices Wakuraba and Mukago nearby as well. Seeing that it is only the Lower Ranks that have been summoned to the Infinity Castle, he wonders on the whereabouts of Lower Five. Before long, Nakime strums her biwa to take them all to a platform in front of her; Rokuro, Wakuraba and Mukago look around their surroundings in fear and uncertainty, while Enmu, being the highest ranking member, calmly looks on ahead. Kamanue sees what Enmu is looking at; an elegantly dressed female demon calmly standing before them. They do not recognize the demon until it utters in a familiar voice, "Lower your heads and crouch down. Prostrate yourselves". Suddenly struck by the demon's aura, the Lower Ranks bow down before the figure. They quickly realize the demon is Muzan Kibutsuji himself: Kamanue grows terrified coming face to face with the Demon Progenitor, sweating profusely at his incredible ability to disguise himself completely and flawlessly. Mukago attempts to apologize on the behalf of her peers, only to be silenced by Muzan for voicing her "worthless thoughts". Muzan states that they are in the castle for only one reason. He tells them about the death of Lower Five Rui, and demands to know why they are so weak. He tells the Lower Ranks that as members of the Twelve Kizuki, all they should do is eat humans and gain strength, as it is only then that they can be useful to him. He compares them unfavourably to the Upper Ranks; while they have not changed positions in over 100 years and have killed members of the Hashira, it is the Lowers who continue to change and get replaced. Kamanue finds it unbelievable that Muzan is placing seemingly impossible expectations on the Lower Ranks, only for Muzan to repeat and say his thoughts out loud: "That's easy for you to say, but we...". He realizes this and panics that he has been caught outright and Muzan grows enraged at this act of doubt in his methods. He demands that Kamanue continue speaking his mind; when Lower Six does not responds, he is grabbed and hoisted into the air by Muzan with a large and monstrous arm. Kamanue tearfully begs for forgiveness but is ruthlessly devoured by the unfeeling and cold Muzan; his blood sprays across the platform and Rokuro, Wakuraba, and Mukago are left paralyzed with fear over his gruesome death. Enmu remains obedient and continues bowing down. Wakuraba wonders if he too will be killed, despite all his efforts to attain his position in the Twelve Kizuki and believing he was destined to achieve more. Muzan questions them on whether they fear the Demon Slayers more than they fear him; Wakuraba panics and nearly says a word, only for Mukago to speak up and deny her fear of them. He challenges her and claims that all she thinks about when encountering the Hashira is trying to escape. Mukago tears up under the pressure and defends his honour, claiming that she would put her life on the line for him. However, Muzan only sees her begging as refuting his statement, and Mukago can do nothing but watch as his monstrous arm is brought down onto her, crushing Lower Four instantly. He proceeds to devour her remains and absorb her. Realizing their minds are being read and that they will be killed regardless of what they say, Wakuraba tries to think off an escape plan. Knowing they are powerless to fight him, he sees Muzan is busy absorbing Mukago's body and leaps up from the platform with immense speed. He sprints around the Infinity Castle's walls and platforms, traversing the unusual gravity and making his way further and further from the center; Enmu sees his actions and calls him a fool for doing so. Lower Three manages to gain a considerable distance but suddenly finds himself back in Muzan's hand as a severed head; Muzan states that it would be best if the Twelve Kizuki is made up of only the Upper Ranks, hence why he is killing them. Wakuraba is stunned as he did not hear the sounds of the biwa, nor why he is not regenerating. Muzan hurls the demon's head in front of the last two Lower Ranks and asks if they have any last words. Rokuro asks for a reprieve and promises to be of use to him. When Muzan asks how long of a reprieve and how he intends to do so with his current strength, Lower Two asks for a portion of his blood, swearing to acclimate to its power without fail and to fight as a stronger demon for him. Angered, Muzan asks how he can simply order him for his blood and brands the demon as shameless for his actions. Rokuro begins begging for forgiveness and states that he has misunderstood his intentions, only to have his master silence him and state that his word alone is absolute. Muzan claims he is never wrong and coldly states that he deserved to die, because "You tried to tell me what to do". As Rokuro's blood spill off of the platform, only Enmu remains; Wakuraba believes that he too will be killed since their lives hang on to Muzan's mood, as his own life ends. As his last words, Enmu states that the situation before him is his dream, always wanting to die through the hands of his master and speaking of his enjoyment in watching his fellow Lower Ranks' last gasps of life. He feels blessed to see their pain as the despair and agony of others gives him immense joy and thanks Muzan for leaving him last to be killed. The Demon King remains quiet and still, only to suddenly stab Enmu in the neck with a spine from his arm and inject him with a large amount of blood. As Lower One writhes in pain, Muzan praises him for giving an answer he had wanted to hear.

He tells Enmu that the amount of blood he had injected might kill him, but should he survive, he will become even more powerful. Muzan orders Lower One to kill the Hashira and gives him another incentive; should he kill a Demon Slayer wearing Hanafuda earrings, he can gain more blood, much to Enmu's pleasure. Concluding the meeting, Nakime manipulates the Infinity Castle with strums of her biwa, taking Muzan to a balcony at the top and changing Enmu's position to drop him through several doors, landing in an unknown town.

Aftermath
Whilst on the ground, as Muzan's blood flows through him, Enmu sees a vision of his chosen target and becomes excited at the thought of getting more blood once he kills him and a Hashira. He would initiate his plan by locating a train that has been reported to have numerous disappearances on board; perhaps unbeknownst to him, this was the work of two hidden demons on the train. Months later, with over 40 missing passengers reported on the Mugen train, the Demon Slayer Corps dispatches the Flame Hashira Kyojuro Rengoku to investigate, accompanied later by three Demon Slayer: Tanjiro Kamado, Zenitsu Agatsuma, and Inosuke Hashibira, setting in motion Enmu's battle with the Demon Slayers.