All human hearts are the same—fragile and weak like glasswork.
— Enmu to himself in Train of Infinite Dreams
Enmu took the form of an incredibly pale young man with ringed blue eyes that tilt sharply down towards the sides of his face, the left one of which with the kanji for "Lower Rank One" etched into its iris and a horizontal slit on his right instead of a pupil. He had three square-shaped markings on each of his cheeks, each separated by a smaller square, which fade 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 tucked behind his ear. His hair fades into a red-orange color near the ends, but appears blue at the tips of the two longer, shoulder-length strands that curve 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 fall down below his knees, and a white dress shirt, the cuffs of which appear over those of his coat. He also wore a pair of pinstriped pale gray pants and plain shoes of a similar color.
Enmu was very sadistic in personality, and was noted to enjoy 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 suffering of others, enjoying the agonized expressions they make as he tortured them. This sadism even extends to his fellow Demons, as he relished seeing his fellow Lower Ranks 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 was also 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 seems 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 Ranks to a blood duel in order to take their place.
When Enmu was a human being, he had a tendency since childhood not to be able to distinguish the difference between dreams and reality, this caused many problems for the people around him. As an adult, even though he was not a doctor, he misused things like hypnotic therapies, as well as convincing patients who did not have long to live that they had recovered their health. Even though after a while they realized that it was all a lie, he kept doing this horrible scam over and over again.
One night, Muzan wanted to completely devour Enmu. Enmu's guts were eaten by Muzan and he was not supposed to turn into a demon at first, but because he felt no pain from the fatal wound, he envied and praised Muzan. With those last words, his heart and brain stopped working, so Muzan turned him into a demon. Enmu knew that he had been converted due to Muzan's whim and would only remember him in passing, so Enmu did his best to ascend to the rank of Lower Moon One.
After all of the remaining Lower Ranks gather together at the Infinity Castle, 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 Rank 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 Kizuki 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 more than a century since the Upper Ranks were last replaced, yet the Lower Ranks 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 Rank by his neck and lift him into the air.
A terrified Kamanue attempts to apologize, but was promptly eaten by Muzan as Enmu and the rest of the Lower Ranks 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 Rank, and, simultaneously, Mukago thinks about how she runs every time from the very mention of a Hashira. 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 Infinity Castle 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 Ranks 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 Rank 2 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 Rank 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 Ranks, thanking his leader for leaving him until last. Muzan then changes his mind as he glances at Enmu. Enmu was then stabbed by a needle-like appendage in the neck and given a generous amount of Muzan's blood, with Muzan telling him to be useful to him by killing the Demon Slayer Corps' Hashira. Muzan promises that if he kills the demon slayer with Hanafuda earrings, Tanjiro Kamado, Enmu will get even more blood. Enmu is then sent out of the hideout onto a street. Enmu is then given a vision of Tanjiro, his target, which excites him for more blood from Muzan.
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 Ranks with his newfound strength. An enraged Tanjiro attempts to attack the Lower Rank, 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 Rank 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 Ranks 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.
Overall Abilities: As Lower Rank 1, Enmu was the strongest Lower Rank and closest to matching the strength of the Upper Ranks. 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's nowhere near the level of an Upper Rank Demon and so pales in comparison to the likes of Daki, Gyutaro and Kaigaku, the least among the Upper Rank.
Enhanced Speed & Reflexes: As a member of the Twelve Kizuki, Enmu harbors an extremely high concentration of Muzan Kibutsuji's blood in him, which enhances and augments his movement speed as well as his physical and mental reaction time and reflexes. This is shown during his battle against Tanjiro Kamado in the movie adaptation, where he was able to dodge and react to every single one of Tanjiro's attacks with little effort, even moving so fast that he had trouble keeping up.
Flesh Manipulation: Like all Demons, Enmu possesses the ability to manipulate his own flesh. After fusing with the train, Enmu uses this ability to attempt to consume the human inhabitants on board and to attack the Demon Slayers on board.
- Flesh Detachments: Enmu shows 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's able to create a detachment as large as a human body in order to fool others into thinking that it was his real body.
- Fusion: Enmu also displays the ability to absorb and incorporate himself into large, inanimate objects. He's able to assimilate a train and transform it into his main body, planning on eating the over 200 passengers on his new train body.
Dream Manipulation: Enmu's main ability is his power to enter, manipulate and control someone's dreams. He's even capable of essentially killing someone by destroying their "Spiritual Core" inside the dream, effectively destroying their mind and leaving their body as an empty shell. However, it's to be noted that there's 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 is touched by Tanjiro's inner kindness and subsequently loses his will to kill him. For this reason, Enmu, instead of entering the minds of his victims himself, always has someone else enter into the target's dream.
- Connecting Rope: Enmu can 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 themself then fall asleep by counting backwards.
Sleep Inducement: Enmu has displayed the ability to cause people to fall asleep instantaneously either directly or indirectly.
- Sleep Tickets: By mixing in his blood with ink on train tickets, Enmu can put anyone who held them to sleep, thus making them vulnerable to his powers.
- Whispers of Forced Unconscious Hypnosis (
強 制 昏 倒 催 眠の 囁き Kyōsei Kontō Saimin no Sasayaki?) - A mouth forms on the back of his hand, which tells the target to sleep and forces them to fall asleep.
- Eyes of Forced Unconscious Sleep (
強 制 昏 倒 睡 眠・ 眼き Kyōsei Kontō Suimin - Manakoki?) - Enmu creates dozens of eyes on his flesh on which the kanji for Dream ( 夢Yume?) is engraved on their irises, and, upon looking into them, the target falls asleep.
Bone Awl: Enmu can create an awl with the handle made with one of his bones and the sharp point made from one of his teeth. Enmu's awls are capable of piercing and destroying the spiritual core once it is found within the subconscious realm of a person's dream. They are more powerful than a normal tool as it was able to pierce Tanjiro's Demon Slayer Corps uniform, despite the uniform being resistant to the claws and fangs of minor demons.
- Enmu's name is made up of the kanji for "to have a nightmare" (
魘en?) and "dream, vision" ( 夢mu?).
- Enmu's rankings in the popularity polls are as follows:
- Enmu ranked 22nd in the first popularity poll with 109 votes.
- Enmu ranked 16th in the second popularity poll with 2435 votes.
- (To himself) "All human hearts are the same—fragile and weak like glasswork."
- (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!"
- "To be able to die while dreaming... just how luck are you? [...] Falling deeper into their sleep, deep in their dreams. Forget to breathe, deep in their dreams. And even if a Demon comes, deep in their dreams. Even in the stomach, deep in their dreams. [...] You are falling... you are falling... into a dream. It's a deep slumber. They can... no longer awaken."