Enmu, a primary antagonist in the *Mugen Train* arc, occupies Lower Rank One in the Twelve Kizuki hierarchy, serving Muzan Kibutsuji. Born human, his childhood blurred the lines between reality and dreams, fostering manipulative tendencies that defined his adulthood. Posing as a doctor, he exploited dying patients with fraudulent hypnosis and treatments, promising false cures. His human life ended when Muzan, intrigued by his apathy toward pain and latent cruelty, mortally wounded him before granting demonic transformation. As a demon, Enmu specializes in psychological warfare through his Blood Demon Art: "Dream Manipulation." By distributing tickets laced with his blood, he induces sleep to invade victims’ dreams, severing their spiritual cores to trigger mental collapse. Ropes tether dreamers to external agents tasked with annihilating their subconscious defenses. After consuming extra blood from Muzan, he gained autonomous flesh fragments, a hand-mounted mouth for hypnotic whispers, and the ability to fuse his body with the Mugen Train, weaponizing it to devour passengers. Enmu exhibits sadistic delight in others’ suffering, relishing executions of fellow Lower Moons and manipulating human allies with empty vows of serene dreams. Though fiercely loyal to Muzan, he harbors insecurity over his power, resentful of his inferiority to the Upper Ranks even post-enhancement. His ruthless cunning clashes with overconfidence, underestimating adversaries like Tanjiro Kamado’s will to sever dreams through self-harm or Inosuke Hashibira’s resistance to hypnosis. In the Mugen Train conflict, Enmu merged with the locomotive to consume passengers while trapping Demon Slayers in tailored dream illusions. After Tanjiro disrupted the dream invasion by stabbing his neck, Enmu’s secondary form was beheaded. His true body, fused with the train, disintegrated when Tanjiro and Inosuke destroyed the hidden neckbone within the engine. Dying moments revealed his morbid fixation on anguish, expressing despair yet perverse gratitude for witnessing agony—a final testament to his obsession with suffering as transcendence.