Enmu

Enmu is a member of the Twelve Demon Moons, holding the position of Lower Moon One.

Appearance
Enmu took the form of an incredibly pale young man, with ringed blue eyes that were tilted sharply down towards the sides of his face, the left one of which with the kanji for 'Lower Moon One' etched into its iris and right with a short horizontal line rather than a pupil. He had three square shaped markings on each of his cheeks, each separated by a small dot, which faded from green to yellow in color, and straight, chin-length hair of a dark black color which he wore parted to his right, the right side slicked back behind his ear. His hair faded into a red-orange color near the ends, but appeared blue at the tips of the two longer, shoulder length strands that curved upwards and outwards below the base of his neck, from under the rest of his hair.

Enmu wore a long, black button-up coat that arched upwards on either side of his legs so that only the two tails in front and behind fell down below his knees, and a white dress shirt, the cuffs of which appeared over those of his coat. He also wore a pair of pinstriped pale gray pants and plain shoes of a similar color.

Personality
Enmu was very sadistic and enjoyed the pain and suffering of humans, his favorite method of torment being giving them a happy and pleasant dream before turning it into a nightmare. He took pleasure in the pain and suffering of others, enjoying the agonized expressions they made. This sadism even extends to his fellow Demons, as he relished seeing his fellow Lower Demon Moons being killed right in front of his eyes.

Like most Demons, Enmu was shown to have little to no care for human life, seeing humans as nothing more than mere pawns, as he doesn't bother to warn his human minions of the various dangers of facing Demon Slayers, simply considering them to be expendable. He also seemed to revel in turning humans into his desperate servants by using his power to give them nice and pleasant dreams, before pulling them out and falsely promising to give them more if they help him.

Enmu has also shown to be intelligent and cautious, having complete understanding of his power's strengths and weaknesses and making sure to both exploit and avoid them respectively in order to succeed. However, upon being given more blood and therefore further empowered by Muzan, Enmu seemed to have become overconfident, arrogant and greedy, as seen when he began to act more recklessly to obtain more blood from Muzan in order to properly challenge one of the Upper Moons to a blood duel and take their place.

Functional Recovery Training Arc
After all of the remaining Lower Moons gather together at the Dimensional Infinity Fortress, Muzan appears before them in his female form. He regards them with annoyance and tells them to lower their heads and squat in front of him. After they all do so, Mukago utters that she's sorry to have been ordered to bow, as she didn’t recognise Muzan in his current form. Muzan angrily asks why she's speaking without permission, telling her to silence herself and not to talk unless directly asked a question. As she cowers in fear at her feet, Muzan goes on to explain the death of Rui, the only Lower Moon who wasn't among the ones gathered before him, and asks the remaining Demons why they're so weak.

Muzan lectures them about how being in the ranks of the Twelve Demon Moons isn’t the end; it is only the beginning of what is to come. He states their sole purpose is to consume blood so they can be of use to him. Muzan angrily retorts that it has been hundreds of years since the Upper Moons were last replaced, yet the Lower Moons are replaced all the time, to which Kamanue thinks to himself that he can’t just tell them that. Capable of reading the minds of those he has shared blood with, Muzan angrily asks Kamanue why they couldn’t be told that, expanding and extending his arm into a tentacle to grab the Lower Moon by his neck and lift him into the air. A terrified Kamanue attempts to apologize, but is promptly eaten by Muzan as Enmu and the rest of the Lower Moons keep their heads lowered in a shocked silence.

Next, Wakuraba thinks to himself that he's also going to be killed, so he needs to do more in order to keep his position as a Lower Moon, and, simultaneously, Mukago thinks about how she runs every time from the very mention of a Pillar. Muzan repeats aloud both of their thoughts, and a terrified Mukago exclaims that what she thought isn’t true and that she would fight with her life on the line for him. Muzan asks her if she is denying what he was saying, and, as Mukago begins to apologize and cry, another bout of Muzan's tentacles crushes her into the ground, killing her.

Shocked by this, Wakuraba immediately assumes the worst and decides it would be a wiser choice to flee than stay if he wanted to keep his life. He dashes out of the Dimensional Infinity Fortress at a high speed, and Enmu, with a sadistic smile on his face, thinks to himself that that was a stupid move to make since Muzan will kill him either way. This conclusion turns out to be correct, as Wakuraba's head is swiftly chopped off, so fast that it leaves him wondering how he even died in his final few moments.

As one of the two Lower Moons left alive, Rokuro then panics, exclaiming that he can definitely still be useful to Muzan if he just defers his death for a little longer. Muzan asks how he would be useful, how long the deferment would last, and how much power he could wield as he was, and Rokuro explains that if he had more of Muzan's blood, he can adapt it and definitely become a strong fighter worthy of his leader. Muzan angrily tosses Wakuraba's head down next to Enmu and Rokuro, asking Lower Moon Two why he should be given more blood and saying that he should know where he stands. Rokuro tries to protest, but Muzan silences him and says that, since he had attempted to instruct his leader, Rokuro deserved to die. After killing Rokuro, Muzan turns to the last Lower Moon left, Enmu.

When asked for his final words, Enmu expresses joy at Muzan killing him personally and for the suffering of humans and his fellow Moons, thanking his leader for leaving him until last. Muzan then changes his mind as he glances at Enmu. Enmu is then stabbed by a needle-like appendage in the neck and given some of Muzan's blood, with Muzan telling him to be useful to him, along with the orders to kill the Demon Slayer Corps' Pillars and Tanjiro Kamado. Rolling around on the floor in agony, Enmu nevertheless laughs, Muzan's promise for more blood the only thing on his mind.

Demon Train Arc
Later, he stands upon the steam engine, remarking that dying while dreaming is a blessing. One of Enmu's hands speaks with the train's conductor about the success of putting the Demon Slayers to sleep and did the same to him. It then addressed the other conspirators, cautioning them about how to proceed with their plan and of its host's temporary inability to move. Back on top of the train, Enmu's main body reflects on his plan to destroy his targets' spirit cores, rendering them completely vulnerable, and of the fragile nature of human hearts. As his plan begins to unfold, he notes his victims' inability to wake up and stop his twisted scheme.

Enmu then notices that his human pawns were having trouble destroying the spirit cores, but decided that it was alright as they were simply buying time. Shortly thereafter, he turns as Tanjiro approaches him, greeting him and stating that he showed him a pleasant dream, but could have made it a nightmare. Smiling, the Demon then tells Tanjiro that his next dream would be of his father coming back to life.

Enmu muses over his enjoyment of first showing humans pleasant dreams and then giving them nightmares, as well as the finer details of his plan, but also wonders how Tanjiro figured out how to wake himself so quickly. He then notices the Demon Slayer's earrings, much to his joy, his thoughts solely on receiving more of Muzan's blood and challenging the Upper Moons with his newfound strength. An enraged Tanjiro attempts to attack the Lower Moon, but Enmu quickly puts him to sleep. The youth just as quickly breaks Enmu's technique, despite the Demon's multiple attempts, leading the surprised Lower Moon to compliment his determination. His neck is then severed by the furious Demon Hunter, but an unfazed Enmu merely states that he now knew why his leader wants Tanjiro dead, and reveals to the shocked youth the reason for his continued survival: he had fused with the train while they had all slept. Taunting Tanjiro to protect the two hundred passengers inside of him, Enmu's severed head merges into the train.

Thanks to Tanjiro and Inosuke Hashibira's joint effort, they manage to discover Enmu's head and subsequently, behead him by completely cutting off the train's top engine compartment. Enmu, in complete disbelief at his failure, begins to curse all the Demon Slayers, Nezuko, and the Upper Moons due to being inferior to them in power. As his body slowly disintegrates, he attempts to at least kill the weakened Tanjiro and Inosuke but only failed once more as his body began to crumble faster. While he dies, Enmu begins to further curse his failure and frantically think that the entire debacle to be a nightmare and demanded to have a redo as he finally crumbled to nothing.

Demon Abilities
As Lower Moon One, Enmu was the strongest Lower Moon and closest to matching the strength of the Upper Moons. Upon receiving more blood from Muzan, his power and abilities were further enhanced. However, as seen from his defeat at the hands of Tanjiro and Inosuke, he was nowhere near the level of an Upper Moon Demon.
 * Regeneration - Like all Demons, Enmu had powerful regenerative abilities. Due to being one of the Lower Moons, it is likely his self healing was above that of average Demons.
 * Sleep Tickets - By mixing in his blood with ink on train tickets, Enmu could put anyone who held them to sleep, thus making them vulnerable to his powers.
 * Connecting Rope - Enmu could create a unique kind of rope by using his own flesh, that, when tied to a sleeper trapped inside one of his dreams and an outsider, allowed the outsider into that person's dreams. To enter into the victim's dreams, the outsider would first have to tie both ends of the rope to him/herself then fall asleep by counting backwards.
 * Fusion - Enmu also displayed the ability to absorb and incorporate himself into large, inanimate objects. He was able to assimilate a train and transform it into his main body, planning on eating the over 200 hundred passengers on his new train body.
 * Flesh Detachments - Enmu had shown the ability to create flesh detachments from his own flesh and blood, being able to create and detach one of his own hands and send it out independent from his main body. Later, upon being given more blood from Muzan, he was able to create a detachment as large as a human body in order to fool others into thinking that it was his real body.

Blood Demon Art: Enmu's main ability was his power to enter, manipulate and control someone's dreams. He was even capable of essentially killing someone by destroying their "Spiritual Core" inside the dream, effectively destroying their mind, but not their body. However, it's to be noted that there was a danger of being affected and possibly mentally changed by the unconscious mind of his victim, as seen when one of Enmu's human agents was touched by Tanjiro's inner kindness and subsequently lost his will to kill him. For this reason, Enmu, instead of entering the minds of his victims himself, always had someone else enter into the target's dream.
 * Whispers of Forced Unconscious Hypnosis (のき) - A mouth formed on his hand, which tells the target to sleep and forces them to fall asleep.
 * Eyes of Forced Unconscious Sleep (・き) - Enmu created multiple eyes on which "Dream" was written, and, upon looking into them, the target fell asleep.

Quotes

 * (To himself): "I must say, I like to show a nightmare after I show someone a good dream. I love to see the contortions of a human face! To gaze upon someone struggling with their grief and suffering—so much fun!"

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