The Day After, With Lynn

"H-Hey, should we really be doing this?" Lynn asked with worry of what they were about to do.

"Quiet! The police are already looking for us! This is the only way we can make it onto the train with our swords! Plus, I'm not letting this ticket go to waste after just buying it!" Zenitsu said as Lynn, Tanjirou, Zenitsu, and Inosuke were sneaking around at one of the newly established train stations in the land.

It had been a day since Lynn parted ways with you, and deciding to follow your advice, she joined Tanjirou and his friends on their adventures in order to hunt down the Twelve Kizuki. A messenger crow had informed them about a demon possibly devouring humans aboard a train. They were also informed that they were to join the Flame Hashira, Rengoku Kyojuro, and assist him in hunting and exterminating the demon that was aboard the large contraption. However, due to looking a bit suspicious in their Demon Slayer uniforms and the fact they were armed with swords, people were a bit scared and police were onto them. Managing to avoid them and sneak back around on the platform of the station, they found themselves staring at the train they were told to board as the whistle blared its signal that it was about to leave as the steam engine began to leave the station.

"For now, let's hide our swords on our backs." Zenitsu said before noticing the train was about to leave the station. "Oh no! The train's leaving! Are the police still around?" He said while looking around with worry.

"We'll have to go even if they are." Tanjirou said as Inosuke suddenly burst out in excitement.

"AHAAAHH!! I'm taking you on! Lord of this land!" Inosuke said before running out towards the tail end of the train that was exiting the station.

"Hey, idiot!" Zenitsu called out before Lynn suddenly ran pass him to follow her boar masked friend and Tanjirou spoke up.

"We should go, too!" Tanjirou said before running off after them as well.

"Huh? Hey, don't leave me behind!" Zenitsu said before running out of cover as they were running toward the end of the platform.

Inosuke and Lynn both jumped onto the back of the train with ease before Tanjirou followed suit, landing next to them as they turned back around. Reaching the end of the platform, Zenitsu was forced to jump on the tracks and run as fast as he could after the train which was increasing in speed. 

"W-Wait up! Tanjirou! Inosuke! Lynn!" Zenitsu cried out as he grabbed onto the rail of the train.

"Zenitsu!" Tanjirou and the other two reached over to pull Zenitsu onto the rear entrance to the back train car.

Opening the door, Tanjirou led the three of them into the train car that was filled with people minding their own business while traveling on the steam engine. Lynn followed closely looking in amazement of how nice the inside of the train looked, while Zenitsu had to deal with Inosuke who was running rampant in awe and excitement of being inside the train. Tanjirou stopped to help an elderly passenger with her luggage while Lynn was admiring a cute baby she saw in one of the seats, telling the mother how cute her baby was while the baby slept. While continuing down the cars in search for the person they're suppose to meet, Zenitsu spoke up while dragging Inosuke behind him.

"He's a Hashira, right? This Rengoku person...Are you sure you'll recognize his face?" Zenitsu asked while Tanjirou led them down the aisle.

"Sure. He had this gaudy hairstyle, and I remember his scent, too." Tanjirou said as they reached the door to the next car, and Inosuke gasped in excitement that startled the civilians, so Zenitsu dragged him away with speed as they waited at the next door. "I think I'll know it's him once we get close." Tanjirou said as Lynn spoke up.

"Tanjirou, you have a pretty good sense of smell. It's almost as if you're a dog." Lynn said as seemed a bit saddened by this.

"A-A dog...?" Tanjirou said as Lynn panicked while waving her hands.

"I-I'm joking! I'm joking! You're really really REALLY helpful with the amazing sense of smell you have!" Lynn said as Tanjirou just slowly reached to slide open the next door, but the second he did...

"Delicious!!!" A voice suddenly burst out and rumbled the train car they were in as Tanjirou and his friends were stood still in surprise.

"W-What was that?" Lynnn asked as she felt very startled by that shout while Tanjirou slid the door open all the way, revealing surprised civilians who were staring down the aisle.

"Delicious!" The train car rattled everyone once again as Tanjirou led the three of his friends slowly down the aisle as they saw the Flame Hashira himself gorging on an unbelievable amount of bento's from the train station. "Delicious!" Rengoku said again while taking another bite of food. "Delicious!" He said as he chowed down some more before opening another bento box. "Delicious!" He praised the food again as the four young slayers were confused on how to approach him. "Delicious!" He kept singing praises for the food as before raising his head with a great amount of pleasure being visible on his face. "DELICIOUS!!!" He said that word again so loud that the empty bento's bounced from the seats while he surprised everyone on the train car again while continuing to utter that word over and over while eating.

"What's up with this guy...?" Lynn said while staring at him with a raised brow as the Flame Hashira continued to eat the bento's in his disposal.

"Is that the Flame Hashira guy?" Zenitsu muttered to Tanjirou and Lynn as they awkwardly smiled while nodding in confirmation. "Not just some random glutton?" Lynn and Tanjirou again nodded before carefully sliding into the Hashira's view. 

"Um, excuse me..." Tanjirou tried to get his attention.

"Delicious!" Rengoku said again while taking another bite.

"R-Rengoku?" Tanjirou called his name.

"DELICIOUS!!" Rengoku screamed while turning towards them as Lynn yelped while turning white, along with Zenitsu who turned blue while Tanjirou stood there in an awkward cold-sweat.

"Uh, we really get that part already." Tanjirou said as Rengoku finished his final bento and a few train maids came with a large sack trying to pick up Rengoku's finished meals.

"And you're the two kids from that day at the Master's." Rengoku said with his arms crossed as he looked at them all with an enthusiastic smile.

"Yes. And they are my fellow Demon Slayers, Zenitsu Agatsuma and Inosuke Hashibira." Tanjirou introduced the two slayers that Rengoku hadn't met as the Hashira turned his sights to the box on Tanjirou's back.

"I see. And inside that box there..." Rengoku gestured to the box as Tanjirou turned a bit while looking at it on his back.

"Yes. It's my sister Nezuko." Tanjirou confirmed as Rengoku nodded at him.

"Right! That demon we saw that day, huh? Since the Master's acknowledged her, I won't say any word for now." Rengoku reassured Tanjirou as the young boy was pleased while Rengoku turned his sights to Lynn. "And where is the Demon that travelled with you? Is he accompanying you as well?" He asked as Lynn shook her head.

"No, he left after picking up a lead that could lead him to one of the Twelve...uh...? What were they?" Lynn said while trying hard to remember what they were called.

"The Twelve Kizuki." Rengoku reminded her.

"Ah, right! He's following that lead, and told me to fulfill my duties as a demon slayer. He says that with the training he's given me, this is a rite of passage for me." Lynn said while patting the Tenseiga that was hidden behind her back. "I don't wanna let him down, so I came with them to try and become stronger than before." She said as Rengoku gave a hearty laugh.

"Ahahaha! I see. Although it seems strange to most that a demon would care for a human, it seems you and him have a deep bond that even the Master is willing to accept if it means our goals all meet the same end. A rite of passage, that's something that you should be happy to take on, young one. It means he's placed a lot of faith in you. Do your best!" Rengoku said to her as the smile widened on her face.

"Yes, sir!" Lynn gave him a toothy smile as Regoku patted the seat next to him.

"Have a seat here." Rengoku gestured as the four slayers took their seats, Tanjirou sitting next to Rengoku, Lynn sitting with Nezuko across from them, and Zenitsu with Inosuke in the booth across the aisle. "What are you four doing here? A mission?" Rengoku asked with curiousity.

"We received an order from a Kasugai Crow. 'The casualties of the Mugen Train are increasing. Join Rengoku on site,' he said." Tanjirou informed him of the mission they were all given.

"Yes! I see now! Understood!" Rengoku said while sitting straight up with a proud smile on his face.

"Right." Tanjirou said as there was a brief moment of silence before he spoke back up. "Also, there's one more thing. Something I wanted to ask you, Rengoku." Tanjirou informed the Flame Hashira.

"What is it? Let's hear it." Rengoku asked while Lynn slightly opened the box next to her to peek inside at Nezuko.

"About my father..." Tanjirou trailed off as Rengoku spoke up.

"What about your father?" Rengoku asked him.

"Well, he was really frail." Tanjirou said while finding it hard to describe what he wanted to ask.

"Was he really?" Rengoku said while listening intently.

"But even if it was cold enough to freeze your lungs, he could still perform a kagura dance in the snow." Tanjirou described while the two never exchanged glances.

"Well, I'm glad to hear it!" Rengoku said as Tanjirou was beginning to feel awkward. "The thing is...!" Tanjirou trailed off.

"What's up?" Rengoku also raised his voice to be like Tanjirou.

"Hinokami Kagura...Dance! I suddenly found myself doing the kagura that I'd seen as a child. If you know anything about that, Rengoku...I was hoping you'd tell me." Tanjirou asked as there was a moment of silence while Lynn happily played with Nezuko who was in her box before Rengoku spoke up.

"Right!" Rengoku said as Tanjirou turned towards him. "But I know nothing!" He exclaimed straight forwardly as Tanjirou was surprised by this fact. "I've never even heard the term 'Hinokami Dance' before. But it's truly commendable that your father was able to adapt his kagura dance to battle. All right, end of discussion!" Rengoku ended the conversation as Tanjirou was not ready to end it yet.

"Um, can you try to help me a little more?" Tanjirou asked before Rengoku suddenly shined with ethusiasm.

"You should become my Tsuguko, my apprentice! I'll look after you!" Rengoku offered the position of Tsuguko to Tanjirou.

"Hold on a second! And just what are you looking at?" Tanjirou asked wondering what the Flame Hashira was looking ahead towards when there was nothing in front of him.

"...Good girl, Nezuko~ Good girl~" Lynn turned back and said while gently rubbing her finger against Nezuko's cheek as the young demon girl hummed comfortably while seeming to fall asleep in her box.

"Flame Breathing has a long history. In any given era, there's always been a Flame and Water swordsman among the Hashira. Flame, Water, Wind, Stone, Thunder. Those are the fundamental breathing techniques. The other techniques were created as offshoots of those five. Mist is a fork of Wind. Young Mizoguchi! What color is your sword?" Rengoku asked as Tanjirou seemed a bit saddened at what he was being called.

"Eh? My name's Kamado. And the color is black." Tanjirou said.

"A black sword, huh? Well, isn't that unfortunate? Ahahahaha!" Rengoku gave a hearty laugh.

"For real?" Tanjirou asked, still processing being told the color of his sword is unfortunate.

"I've never known a swordsman with a black sword that became a Hashira. On top of that, I hear that they have no clue which style to master. Come to me, and I'll train you! You can rest easy!" Rengoku said with an even louder and persuading tone.

"No, thank you! And just what are you looking at?" Tanjirou respectfully declined the offer.

"What about you, young girl?" Rengoku asked Lynn as she grew a nervous smile.

"Huh? Me? Uh...Well, I just recently got my color..." Lynn said nervously.

"Come, out with it!" Rengoku coaxed Lynn to speak up with pride.

"U-Um...it's green..." Lynn said as Rengoku gave a hearty laugh.

"I see. Then, maybe you could ask to become the Wind Hashira's tsuguko." Rengoku said to her as Lynn just remembered who was the Wind Hashira, Sanemi.

"Ah, no! I'm sure it wouldn't work out." Lynn said with a scared look on her face when hearing that she should learn from the aggressive Sanemi. "This green just appeared due to the style of combat I've been learning from Lord Y/N. I'm just not too sure what to call it yet." Lynn said while patting her sword that was hidden at her side.

"I understand. Well, I wish you good luck with your style." Rengoku said before closing his eyes to seemingly rest as Lynn just smiled at the genuine tone of his words.

"Thank you." Lynn said as she turned her attention to stare out the window to the starry sky above. "I wonder what he's up to right now..." Lynn thought as she could only think of you during that moment of peace, but was interrupted by the ruckus caused by Zenitsu trying to pull Inosuke, who was hanging out the window, back into the train. "SHUT IT WILL YA!? I'm trying to think of my Lord!" Lynn scolded them.

"That's dangerous." Rengoku spoke up. "You never know when a demon might appear." Rengoku said as this was intriguing news to them.

"You're kidding, right? Demons show up on this train?" Zenitsu asked in a worried tone.

"Sure do!" Rengoku confirmed with a confident and sure voice.

"What?! They do!? Nooo! So, we're not heading to where the demons are, but we're here!? Nooo! I'm getting off--BLEGH!!" Zenitsu was silenced by Lynn who was grabbing his throat with both hands and shaking him back and forth.

"Gosh, every day and night you won't stop screaming!!! I wanna think about my Lord with some peace and quiet! Get a hold of yourself!" Lynn screamed in rage and absurdly wide eyes while shaking a screaming Zenitsu back and forth.

"Over 40 people have disappeared on this train. The corps sent a few swordsmen, but then they all went silent. That's why I, a Hashira, am here." Rengoku explained the situation to them as they all listened closely.

"...HUUUUUUUUUUHHHH!?!?" Zenitsu screamed as Lynn covered her ears in reaction. "Right, I see! I'm getting off! I'm getting off! Uwawawawawawawa..." Zenitsu trembled as the door at the rear of the train car slid open and one of the conductors walked in before closing the door behind him.

"May I...see your...tickets, please?" The conductor spoke in a low and weak tone as this caught everyone's attention.

"What's he doing?" Tanjirou asked.

"The conductor's going to check your ticket and punch a hole in it." Rengoku said while turning and handing over his ticket as the conductor used a ticket puncher and punched a hole in his ticket.

The four slayers all took out their tickets and handed them over to the conductor one by one as he punched holes into each of them. While holding her ticket, Lynn suddenly felt a strange pulse at her side like a heart beat, causing her to tense up a bit in confusion. She felt the side of which the pulse came from and realized that it was the Tenseiga that did something. A feeling of worry came upon her, and she was hesitant to hand over the ticket, but remembering that this was protocol for rides on new public transportation like this, she handed it over anyways. Lynn felt a bit more anxious now and was worried with how pale the conductor was looking at the moment, before suddenly the lights began to flicker before cutting off completely when the conductor punched the final hole in the tickets. The next moment, the lights came back on and Rengoku opened his eyes and Tanjirou also reacted strangely and was on edge.

"Huh? What's wrong, Tanjirou?" Lynn asked with concern.

"What is this? There's a horrible scent." Tanjirou thought as he was looking around the train car to find where it was coming from.

"Thank you...very much." The conductor said with a deathly look in his eyes as Lynn was completely nervous now and worried about the train she was currently riding.

While Lynn was feeling off nerve, she was snapped out of any thoughts when Rengoku suddenly climbed from his seat and stood in the aisle. With a few movements, his haori kicked up and he revealed his blade while standing in front of everyone with that same smile he always wore.

"Mr.Conductor...You could get hurt, so please step back. As this is an emergency, please overlook the fact that I have a sword." Rengoku said as Lynn looked up in worry when the lights began to flicker over and over again before out of thin air, a horrendous demon revealed itself in the aisle near civilians.

"A-A demon...? From where?" Lynn said with shock as the civilians near it were all shocked and horrified, trembling in their seats while it slowly stood up to nearly hit the roof with its head.

"Was it a Blood Demon Art that hid that massive body?" Rengoku asked while moving his blade to his other hand and sliding it into place on the left side of his hip, held with a belt. "I had a hard time detecting you." He said as Lynn grew wide-eyed when the air around Rengoku began to heat up and swirl while he unleashed his red-flamed blade from its sheath. "But if you bare your fangs at innocent people...my bright red Flame Blade will burn you to the bone!" Rengoku proclaimed a warning to the beast as the foul demon unleashed a roar that shook the train car and made everyone tense up.

"H-Here it comes...!" Lynn said while moving back a bit with the others.

"Flame Breathing..." Rengoku prepared himself, squaring up while reeling his blade back to his right side. "First Form..." He tightened the grip on his blade as the demon launched itself at him, but Lynn couldn't believe what she was seeing because as if the individual flames on his sword lit up one at a time, Rengoku burst forward at unbelievable speeds, dashing pass the demon and beheading it with one strike from the back. "Unknowing Fire!" Rengoku flew all the way through the door on the other end of the train car and burst through, sliding against the wood floor and glancing back from afar as the four slayers watched the dead demon suddenly burst into ashes.

"Amazing. He sliced off the demon's head with one blow." Tanjirou said as Lynn was about to say something, but felt the Tenseiga suddenly begin to rattle at her side.

"Huh? What's wrong, Tenseiga?" Lynn thought while trying to hold it and stop it from rattling as she turned to see Rengoku looked at the other door to the car next over. "Is there another demon?" Lynn thought in disbelief.

"There's still one more. Come with me!" Rengoku said as he ran off ahead to the other train car, with Tanjirou and Lynn both pulling out their swords and running after him.

"Huh?!" Zenitsu gasped in shock of hearing there was another demon.

"All right!" Inosuke exclaimed in excitement while following after the two.

"D-Don't leave me behind!" Zenitsu yelled with fear while running after them while the Mugen Train blared its horn once more.

The steam engine ran full speed along the tracks under the moonlight above, and hovering above in the sky and staring down at the runaway train, you watched closely as you could sense and smell the work of a demon.

"So it's begun, then...Well, the real one I want hasn't revealed themselves yet. This will be ample opportunity to test if she is capable enough to take on Muzan at all. The technique I showed her is near impossible for a human, but if she can do it, then she will be unrivaled by any demon that stands in her way." You thought as Lynn continued to push ahead with her friends, taking up arms to do whatever they can to protect everyone on board and put a stop to the demons that lurk among the Mugen Train.