The Demon Slayers vs Enmu was a battle that took place on the Infinity Train. It focuses on the battle between Demon Slayers Tanjiro Kamado, Zenitsu Agatsuma and Inosuke Hashibira, Demon Nezuko Kamado and the Flame Hashira Kyojuro Rengoku against Lower Rank One Enmu.
Tanjiro is infuriated by Enmu's comments and immediately readies the Water Breathing, Tenth Form: Constant Flux in order to behead Enmu as he unleashes his Blood Demon Art: Whispers of Forced Unconscious Hypnosis. Enmu tells Tanjiro to go to sleep as his hand mouth releases the Blood Demon Art, forcing Tanjiro to lose consciousness and sleep. However, the Demon Slayer quickly regains consciousness and keeps engaging the Lower Rank with the Water Breathing. Enmu continues using his Blood Demon Art to make Tanjiro fall asleep but keeps waking up from him killing himself in his dream. This keeps happening until Enmu decides to make Tanjiro see his family angry and disappointed at him for them believing that he let them die from a demon. With his own siblings, mother and even his father insulting him, this angers Tanjiro knowing that his family would never badmouth him under any circumstance. Because of this Tanjiro is able to behead Enmu using the Water Breathing, Tenth Form: Constant Flux.
As Tanjiro beheads Enmu, he comments that there was no reaction from Enmu being beheaded leading him to believe that whether he himself was in a dream or if he was just overall weaker than the previous Twelve Kizuki member he fought, Rui. Enmu however notes that 'that person' commanded him to kill Tanjiro Kamado along with the other Hashira, and he points out that the Demon Slayer's existence makes him seethe in anger. As he is saying this, a huge bundle of flesh connects Enmu's disembodied head to the ceiling of the train. Tanjiro looks in disbelief and fear as Enmu tells him that even a toddler can figure out why he won't die even if he is decapitated by a Nichirin Blade. He describes that this is not his actual body but that he merged with the entire train with it being his flesh and bones. As Tanjiro tries to cut Enmu, his "head" fuses with the train before that happens.
Tanjiro panicking, immediately tries to go back to the passengers to defend them despite him stating that he can only protect two carriages at best. He shouts Kyojuro and the others, begging them to wake up in order to defend the passengers. Suddenly, a faint noise keeps building up from inside the Infinity Train, that being Inosuke Hashibira screaming his catchphrase "EXPLOSIVE AWAKENING!!!". Filled with relief but seriousness soon after, Tanjiro tells Inosuke to take care of the passengers coming to the latter's frustration due to his dream. Inosuke then jumps back into the crevice that he created and unleashes his Beast Breathing, Fifth Fang: Crazy Cutting wanting admiration from the passengers when they wake up, as Tanjiro goes to another carriage through a window he cuts off one of the fleshy ingrowths with the Water Breathing, First Form: Water Surface Slash.
On another part of the Infinty Train, Nezuko Kamado readies herself to defend the nearby passengers from Enmu's ingrowths by slashing, smashing and punching them. Soon after, one of the ingrowths becomes to close to a passenger so Nezuko puts her arm in between the two, taking a hit. As the ingrowth grasps Nezuko's arm, she tries to slash it off with her nails but another ingrowth grips her other arm and soon both of her legs, completely constricting her. Before the ingrowths rip Nezuko apart, a sudden flash of lightning coming from multiple nearby carriages light up and destroy all the ingrowths constricting Nezuko. The flash turns out to be Zenitsu Agatsuma still fallen asleep but with his natural instincts kicking in, with this being said he quickly slashes and destroys all the surrounding ingrowths with his Thunder Breathing, First Form: Thunderclap and Flash, Sixfold. As he finishes the technique, Zenitsu comments to Nezuko that he will do anything to protect her from harm but soon loses focus and goofily finishes his sentence.
On the other side of the train, Tanjiro notices the sound of lightning behind him and questions if Zenitsu and Kyojuro have woken up. Kyojuro is shown shaming himself for staying asleep as the hundreds of passengers were of near-death states as he charges a Flame Breathing technique, presumably being the Flame Breathing, First Form: Unknowing Fire. The sheer impact of his techniques shakes the whole carriage and even nearby ones out of the rail track, enough to make Tanjiro and the others lose their footing. As the Infinity Train finishes derailing, Kyojuro goes into the same carriage where Tanjiro is and explains that there are eight total carriages and he will defend the back five and Zenitsu/Nezuko will defend the other three. With that out of the way, he requests Tanjiro and Inosuke to first defend Zenitsu and Nezuko and then find a weak spot of the Lower Rank in order to kill it.
Tanjiro comes in and saves Inosuke at the nick of time from the ingrowths by using the Water Breathing, Sixth Form: Whirlpool as the chunks of flesh cut off fly far off from the train. Enmu is then heard screeching in pain by everyone even on the very back carriages. From hearing this, Tanjiro believes that the "weak spot" is somewhere nearby and requests Inosuke to open the floor that they are standing on if the Lower Rank's weak spot is residing there. The latter gets frustrated for being commanded around by his "subordinates" and uses his Beast Breathing, Second Fang: Slice towards the floor, revealing large vertebrae-like bones. Tanjiro sees Enmu's neckbone and immediately uses the Water Breathing, Eighth Form: Waterfall Basin in order to behead the Lower Rank but the latter protects his neckbone with flesh before Tanjiro's technique can make contact with the vertebrae.
The flesh that defended the neckbone quickly expands in all directions with fleshy hand-like appendages flailing around. Tanjiro grabs hold of the train conductor and with Inosuke quickly leap to a safe distance as the flesh continues expanding into the structure near similar to an arena. Tanjiro quickly requests Inosuke to help him out in order for their Breathing techniques to combine in order to inflict some harm onto the neckbone but before they manage to do that, Enmu unleashes his Blood Demon Art: Eyes of Forced Unconscious Sleep, forcing Tanjiro to fall asleep constantly. Upon seeing the Blood Demon Art, Tanjiro quickly tells Inosuke to cut his own neck inside the dream in order to wake up. As Tanjiro keeps on waking up and falling asleep, at one point he doesn't know what is reality anymore and positions his Nichirin Blade near his neck ready to cut his own throat in the real world. Before he could do so, Inosuke quickly grabs Tanjiro's wrist and drags it toward the ground to stop him from killing himself.
Inosuke informs Tanjiro that this is reality and continues slashing the ingrowths with the numerous eyeballs with the kanji for "Dream" (
As Inosuke falls towards the engine of the train, he grinds both his Nichirin Blades on the dozens of eyeballs from Enmu's Blood Demon Art and with the momentum of the fall along with his swordsmanship, Inosuke uses his Beast Breathing, Fourth Fang: Slice 'n' Dice to cut away the flesh that protects the neckbone for Tanjiro. With Enmu's neckbone exposed, Tanjiro pleads to his father Tanjuro to help him defeat the final Lower Rank as he transitions between the Water Breathing to the Hinokami Kagura. With that, he uses the Hinokami Kagura: Clear Blue Sky, severing Enmu's head, truly killing him.
With Enmu beheaded, he profusely shrieks in pain and horror as he unleashes his ingrowths to attempt to consume all the 200 passengers onboard presumably to help accelerate his regeneration in order for him to reattach his severed head. They were thankfully stopped by Kyojuro Rengoku and Zenitsu Agatsuma with their respective Breathing Styles.
The entire Infinity Train completely derails as the Lower Rank continues shrieking and the ingrowths flail everywhere. Tanjiro begs to Inosuke and the others to defend the passengers at all costs, however his comments soon stop as the hemorrhaging in his abdomen continues. Inosuke concerned at Tanjiro asks if his wound is okay with the latter responding that it is okay and that he should focus more on the passengers. Panicking, Tanjiro realizes that if he dies the train conductor will be a murderer due to his abdomen wound being evidence for his "murder". As the Infinity Train collapses onto the terrain, Tanjiro tries his hardest to grasp the train conductor but to no avail. Thankfully, his impact onto the ground was rather soft due to him rolling because of the momentum of the train.