The Mugen Train continued barreling down its tracks and blared its horn as Tanjirou and Lynn both flung themselves atop the train where they then turned run towards the front of the train. While running towards the steam engine dragging the rest of the train behind it, Lynn found it difficult to stay awake and was having trouble staying on her feet. Using the Tenseiga was much more taxing than she initially thought it was, but despite this handicap she gave herself, she had no regrets and continued ahead to fulfill her duty. She kept her pace behind Tanjirou as the two slayers both reached the second train car behind the caboose where they stopped in their tracks when they found themselves staring at the back of the demon, Enmu. Noticing their presence behind him, the sleep demon glanced with a smile plastered on his face as Lynn and Tanjirou both raised their guards while staring down the demon.

"What? You're awake? Good morning!" Enmu turned around and gave them a shilling smile and wave as he pointed his hand to aim the mouth on his hand towards them with its creepy smile. "You could've stayed asleep." He said in a teasing manner as Tanjirou and Lynn had their hands ready to draw their swords.

"It was him!" Tanjirou concluded after hearing his statements and connecting everything in that moment.

"You bastard..." Lynn muttered in a low fierce tone.

"Why did you wake up? Didn't I show you a sweet dream? I could've shown you a dream where your family was being slaughtered. Would you have liked that one better? No, of course not. Too distressing, right?" Enmu spoke in shrill voice as the two slayers were confused about what he was going on about. "All right, next...Why don't I show you a dream where your father comes back to life? Or should I show you a happy life where you're the bride of that white haired man in your dreams?" He teased as this only further enraged Tanjirou to the point where the veins on his head were beginning to show on his skin, while Lynn's pupils dilated and she drew her blade as the veins on her hand were popping out as well.

"I'll make you pay for what you did..." Lynn said as a strange breathing noise became audible when she was taking in air.

"Tch...!" Tanjirou grit his teeth as he tightened his grip on his hilt and the air around the two dispersed for a moment when their breathing techniques kicked in.

"I mixed my blood with the ink on the tickets. Once the conductor punches them, creating clamp marks...the spell activates." Enmu thought as he put away his smile to stare at the two of them with a perplexed face. "And yet...how did these two manage to wake up? And they found a the way to wake up in a short time. Even though the human desire for blissful dreams, for self-serving dreams..." Enmu's thoughts trailed off as he smiled once more at the two of them. "...is so enormous!" He said with excitement as the two slayers began to draw their blades.

"Don't you dare intrude on my soul!" Tanjirou yelled as he and Lynn readied their blades. "We won't let you get away with this!" He yelled as Enmu noticed something on Tanjirou's ears.

"What's that? I see he's wearing earrings..." Enmu thought before a creepy smile crept onto his face when he realized who was stood before him. "How lucky is that? So, he came right to me! This is like a dream! Now I can receive even more blood of Master Muzan!" He suddenly raised his hands and exclaimed how thrilled he was feeling. "And once I become more powerful, I'll challenge an Upper Rank demon to a duel to replace him!" He laughed as Tanjirou began to make his move.

"Water Breathing..." Tanjirou raised his katana above his head before lowering it back down to his left side. "Tenth Form...Constant Flux!" Tanjirou readied his attack as Lynn looked with amazement.

"Blood Demon Art!" Enmu raised his hand above his head as the mouth on his hand smiled creepily and Tanjirou charged ahead. "Whispers of Forced Unconscious Hypnosis." He aimed his hand's mouth toward Tanjirou as it opened to speak. "Go to sleep!" It spoke in an unnerving tone as Tanjirou felt a strange force suddenly hit him and he stopped running as he lost consciousness.

"Tanjirou!" Lynn yelled with worry as Tanjirou's eyes shot open, shocking Enmu.

"He's not falling asleep." Enmu thought in surprise as he was forced to jump back to avoid Tanjirou's double slash.

"That hand put him to sleep like the ticket. It'll be troublesome if he gets put under the spell for too long. I have to support him!" Lynn thought in desperation as she began to make her move. "My body, please...don't let me down!" She tightened her grip on her blade as raised it up to the right side of her head while the tip pointed towards Enmu.

Days Before The Mission, Butterfly Manor

You and Lynn were stood in one of the gardens in the butterfly manor as you were currently helping Lynn with her training. Lynn was gasping for air as sweat dripped from her face and onto the ground below her while she could barely keep herself off the ground with support of her blade. You stood by watching her closely as she struggled back up to her feet. After finally standing back up, she shakily raised her blade once more as her eyes were wide, trying to focus all her energy to performing the technique.

"Your body has yet to become strong enough to be able to handle the backlash of this technique. You are still healing and with the medicinal remedies they are giving you, you are not at your full potential." You said to her as Lynn kept struggling to stay standing.

"I can...k-keep going...!" Lynn gasped while trying to catch her breath.

"You've just created a breathing form based off my Poison Claw, and the technique I've shown you is a move that even master swordsmen from ages ago couldn't have imagined mastering." You said as you walked over to Lynn and she turned in surprise when you offered her a gourd of medicinal water. "Take better care of yourself first. Once you are well and able to move your body. The technique will be much more easier to perform." You said as she stared up at you, caught by your natural beauty and handsomeness.

Back To Present

"This new breathing form and technique should be capable now. I can do this...!" Lynn thought she began to suck in air through her teeth. "Poison Breathing..." She released one hand from her hilt and held it forward in a claw shape aimed towards Enmu. "First Form...Toxic Spiral Vortex!" She gathered a great amount of strength through her legs as she shot pass Tanjirou with great speeds.

Lynn used all the muscles in her legs to propel herself forward towards the sleep demon ahead of her as she began to spiral through the air in circles with her blade pointed forward. The green sheen that came off her blade made the spiral she was creating glow an ominous green glow as Enmu was forced to retreat an even greater distance when he saw the roof of the train car he was standing on get destroyed by the attack she unleashed. Lynn however with great speeds and before he could finish getting away, stopped spinning and managed to cut one of Enmu's feet off by the ankle. Tanjirou could only stare on in shock as he looked at the massive hole in the train car roof behind Lynn who was stood back up again to glare at Enmu.

"Amazing..." Tanjirou thought while staring at Lynn before looking at the edges of the hole in the train car roof. "The edges looks almost as if they were melted...spinning around in the air like that must have created so much friction on the metal, that it melted when coming in contact with her blade...almost as if acid were dropped onto it." He thought in shock.

"Tanjirou!" The young slayer boy was snapped out of his amazement when he heard Lynn's voice. "Continue the attack!" She screamed as Tanjirou instantly charged forward while Enmu landed on one hand and suspended his body horizontally while aiming his hand towards them and regenerating his foot.

"Go to sleep." Enmu unleashed the spell once more, knocking out Tanjirou, but Lynn jumped over him with a heavy strike readied above her head. "Go to sleep." He casts the spell onto Lynn as she fell unconscious, but luckily landed on her feet as she dropped to her knees, but in that moment Tanjiirou had regained himself and charged in after her. "Go to sleep." Enmu continued casting the spell, but each time, Lynn and Tanjirou were filling in for one another during their charge. "Go to sleep. Go to sleep! Go to sleep!" He was constantly casting the spell while retreating, but the Slayer's tenacity was more than he could handle as they continued to charge ahead. "GO...TO...SLEEP!" The mouth on Enmu's hand screamed as he had a shocked face when he saw Lynn and Tanjirou move in for the fatal blow. "It's not working. But why not?" He wondered in confusion before realizing what was happening. "No, that's not what this is. They're falling under this spell over and over!" He was forced to retreat once more as he dodged Tanjirou and Lynn's attacks, leaping as high as he could as he cast the spell over both of them, making them lose consciousness. "They're aware that they are under the spell right away. And they're committing suicide in order to awaken!" He thought while Tanjirou slit his neck in his dream to wake up, while the Dog Demon in Lynn's dream continued to wake her up by biting her head off.

"HYAAA!" Lynn yelled while launching herself towards Enmu in the air and performing another spiral attack as Enmu was forced to move away, but not without suffering a seething cut on his arms, chest and cheek as he landed on the train, but moved his head to avoid Tanjirou's blade that cut off some hair.

"Even if it's in the middle of a dream, to commit suicide...to take their own life with their own hands...that takes incredible willpower! These brats...are insane!" Enmu could only watch on in shock as the two slayers charged forward with their techniques as he let out the spell, but something was diffrent.

In the dream world, Lynn found herself standing in her home as a red moon shined through the slits of the home where blood dripped from everywhere. Crying echoed through the house as she watched her bloodied and cut up mother console her slashed up brother in her arms. Lynn couldn't breath at the moment from the sight she was being shown as Shosuke spoke up.

"Big Sister...abandoned us...! How...!? How could she...?!" Shosuke cried as Lynn's mother glared at her.

"I knew I should have never given birth to you. You were the one thing I regretted in my life." Lynn's mother spat in a venomous tone as the scene suddenly changed and an axe struck a blood log.

"I should've sold you off to a brothel or some whore house...at least then you could've made us some money..." Lynn's father who was missing an arm and half his face spoke with disgust while staring down at his daughter. "No, you're so worthless, not even the world's ugliest pig would take you for a bride..." He spat blood onto her face as the scene changed once more and she was stood in front of her home, wearing her Slayer uniform while her family all glared at her from inside the home.

"You don't deserve to live in this world. This was all your fault." Her family all blamed Lynn in the dream as she felt her heart almost shatter.

Lynn began to despair and couldn't even think straight anymore after hearing such horrible things from the people she loved the most. Though, even after almost giving in to the spell, the Tenseiga at her side rattled as a glowing hand was placed on Lynn's shoulder behind her.

"Lynn..." The young girl gasped when she heard the voice of someone she knew all too well. "...wake up." The voice said as Lynn's face turned to that of rage and she felt something snap inside of her as she woke up all on her own and glared at Enmu with all her hate as she and Tanjirou both slammed their feet down, denting the train car below them.

"THERE'S NO WAY THEY'D EVER SAY THAT! NOT EVER! NOT MY FAMILY!" Tanjirou and Lynn both screamed at the top of their lungs as Lynn unleashed her first form again while Tanjirou leaped into the air. "DON'T YOU DARE...INSULT...MY FAMILY!!!!!!" They threw all their might at Enmu while remembering the loving families they came from and how much love they gave to them even after their deaths.

Lynn barreled forward with her attack and shredded everything in her way before her blade shredded Enmu's legs so fast, it was as if they were melting. Meanwhile, Tanjirou fell from above with his blade flying forward and striking Enmu's neck before slicing through cleanly as the two slayers both landed ahead of the sleep demon's body. Enmu's upper body fell while his decapitated head rolled away behind them before stopping with his face looking towards the Demon Slayer's backs. The two of them stood back up but didn't put their blades away as Tanjirou looked at Enmu's head, while Lynn stared at the body.

"It was way too easy. Could this be a dream, too? Or was this demon weaker than him?" Tanjirou asked while referring to Rui back on Mt. Natagumo as Lynn shook her head.

"No, Tenseiga would have warned me and tried to wake me up. Something's not right..." Lynn said before the two of them were shocked by what they heard next.

"I can totally see why..." Tanjirou and Lynn turned towards Enmu's head when they heard him speak. "...he ordered me to kill you, the boy with the earrings, along with the Hashira!" They watched in disbelief as Enmu's head suddenly turn into a pool of disgusting flesh as it grew and expanded on the train car. "Your very existence is, like...It couldn't be more irritating, you know!" A tentacle formed from the flesh and extended high above the air his head reemerged with that same unnerving smile.

"No way...! We cut his head off! What's the deal!?" Lynn asked in shock.

"He's not dying?!" Tanjirou gasped as Enmu took pleasure in their shocked faces.

"Oh, that look on your face is so delightful! That's the look I've been wanting to see!" Enmu giggled as the Slayer's readied their blades once more. "You want to know why I'm not dead after you decapitated me, don't you? Fine, since I'm feeling so ecstatic right now. It's so easy even an infant would understand. It's because that body over there was no longer my main body." He said in a shrilling voice as Lynn turned back to stare at the lifeless body in shock as Tanjirou continued to look at Enmu in disbelief. "Same thing with this thing that's talking to you now. It merely looks like my head, but it's not. While you were snoozing away...I fused with this train!" He giggled in amusement as Lynn launched herself towards Enmu.

"First Form! Toxic Spiral Vortex!" Lynn tried to unleash her attack on Enmu, but the flesh sunk into the train, causing her to miss and stop the attack in caution while the flesh reappeared farther from her. "Dammit!" Lynn thought in frustration as Enmu smiled at them.

"Every inch of this train has become my blood, my flesh and bones! Ehehe~! Look at your faces. Are you getting it now? In other words...the more than 200 passengers on this train...are the food that will strengthen my body even more...as well as my hostages. So, do you think you can protect them by yourselves? All these people packing this train from one end to another...Can you two alone keep me from devouring them?" He taunted them with a creepy smile.

"SHUT UP, YOU DISGUSTING FREAK!" Lynn yelled in rage as she and Tanjirou went to cut his head, but Enmu giggled as the flesh and his head sunk into the train and disappeared completely. "Damn! What now!?" Lynn asked while turning to Tanjirou as the young boy looked back to the other train cars behind.

"The others! We have to get them!" Tanjirou said as the two of them began to run back to their friends. "Rengoku! Zenitsu! Inosuke! This is no time to be sleeping! Wake up, will you!? Please!" Tanjirou screamed out while running ahead of Lynn. "Nezuko! Protect the sleeping passengers!" He tried his best to relay instructions to his sister, as the demon girl was currently trying to awaken Inosuke with her Blood Demon Art, and after a few moments, the Boar Head's hand opened fiercely.

The sound of metal being pounded away at could be heard with strange grunts as Tanjirou and Lynn saw dents forming in one of the train car roofs. A few moments later, they smiled when they saw Inosuke shoot out from the train car like the tenacious animal he wore on his head.

"Follow me, damn minions! All right! Explosive Awakening!" Inosuke proclaimed while landing in front of them and raising his blades up ready for battle. "Comin' through! Lord Inosuke's comin' through!" He said with vigor as he all fired up.

"Inosuke! It's not safe anywhere on this train anymore! We have to protect the sleeping passengers! This whole train's turned into a demon! Can you hear me? This whole train is a demon!" Tanjirou yelled as Lynn spoke up as well.

"Hey, Inosuke! You were right about this thing! It's the master of this land! As Lord of the Mountains, it's only right that you take this thing down, right?!" Lynn yelled as this enticed and further coaxed Inosuke on about this train being the lord of the land.

"I knew it! So, I was right on the money! That means I was a total stud as a leader!" Inosuke turned back towards the hole he made as Lynn stood ahead of Tanjirou.

"I'll go and back up Inosuke. You go ahead and try to do whatever you can!" Lynn said before running off. "Let's go, Demon Slayers! Time to stop this train!" Lynn yelled as she and Inosuke leaped into the air and the Slayer's began their operation to save everyone on board the Mugen Train.