Mugen Train Arc (Part 1)

Currently I am sitting in a shop, slowly slurping the delectable ramen noodles. The pleasant presentation of the dish is however interrupted by the person sitting across from me.

"Umai!"

"Rengoku, could you please be a bit more considerate of the shop?" I beg.

Shaking his head, Rengoku promptly answers, "If something is delicious then I must say it aloud!"

"But not on every single bite."

Instead of listening, Rengoku slurps another round of ramen and yells, "Umai!"

Rubbing my temples, a Demon Slayer dressed in a dark blue uniform walks in. Sitting at a table beside our own, the Demon Slayer proceeds to complement Rengoku's work and mine before the old man explains the recent situation surrounding the Slasher and the Mugen Train. Upon mention of the Mugen Train, the Demon Slayer informs Rengoku and I that the Demon Slayer Corps have located it.

Leaving the shop, Rengoku inspects the nearby station where a conductor's body was found. Searching for signs of where the Demon had gone. Upon our inspection of the station, we come across a Ekinaka (Shop inside Station) and Rengoku, being himself, bluntly asks them of the Demon which has been called "The Slasher" by the public.

Using his infinite amount of cash, Rengoku proceeds to buy all of the bentos from the Ekinaka, and then we then leave our Demon Slayer helper behind and board a train heading to shed. Being questioned by the conductor of the train, we learn that the Mugen Train had been transported to a well-equipped maintenance facility that morning.

It just so happened that the train we were on was passing that location, and the two of us being Hashiras, proceeded to jump from the back of the moving train and make our way towards the facility. In the very middle track, there stood the train with the nameplate of "Mugen" plastered to the front.

Letting Rengoku deal with the people, I decide to deal with the presence that'd been bothering me for quite some time now.

Following the man who was to deliver a bento to Tatsu, I come face to face with a bald middle-aged man of a reasonably muscular build with a lime green iris, a black sclera and vertical slits for pupils along with sharp pointed nails that are dark blue in color and several prominent fangs in his mouth. The Demon's entire body is covered in dark blue tattoos, running across various places on his face, limbs, and torso.

Upon our eyes connecting with one another, the Demon quickly grabs Tatsu, and starts to use him as a body shield. Digging his hand into Tatsu's chest, the Slasher quickly scrunches his nose.

"Ugh! This boy's blood smells like it might be revolting. I'll just devour the humans that seem tasty, but the one that taste bad… I like to show myself a good time by tormenting them all night."

"Didn't really think that this would be the way the Slasher acts, but now that I see it, I find you offensive."

"If you don't like me, then…" Moments after saying that his tattoos light up a bright blue and he speeds past my face. "let's see you slash me!"

Unimpressed with his supposed high speed, the Demon continues to brag about himself. However, one of his brags allows for Rengoku to inform him that the woman he supposedly killed still lived and his injuries to her wouldn't even leave a scar. Grasping onto whatever reason he can get; Slasher then starts to say he'll kill the bento family as well as Tatsu.

As his fingers dig deeper into Tatsu's skin, Rengoku flashes past me and removes Slasher's hands. Dropping the boy, Slasher then flies past me and onto the tracks. His tattoos then supercharge, and he breaks the speed of sound, running away.

"Well, I'll see you in a minute Rengoku."

Following the Demon, I put myself into a track start and use 'Total Concentration Breathing' to dramatically increase my speed. Like a flurry of ice, a faint blue residual trail comes into view.

Back at the station I began at, I walk through the halls of the station, and see Slasher standing in the shadows, seemingly talking to someone.

"You know, for a Demon with a speed Blood Demon Art, you're rather slow."

Whipping his head around, I dash forward and use 'Ice Breathing First Form: Frost Fang', decapitating Slasher, causing him to disintegrate moments later.

Making my way back to Rengoku, the two of us board the train when it's re-placed on the track in the evening. Upon receiving our ticket for the train, I get a slightly weird feeling and then place it up against my nose. Rengoku, upon seeing my action, does the same thing, and his smile fades from his face. Nodding our heads to one another, we comfortably seat ourselves.

Partaking in the bentos that were so graciously gifted to us by the Bento Vendors, Rengoku destroys the peaceful serenity of the train.

---

Coming up to us while Rengoku screams aloud "Umai!", Tanjiro and Zenitsu come into view.

Looking at them confusedly, as to why they were on the train, Tanjiro quickly gives me a hug. Sitting next to me, Tanjiro is quick to tell me of all that had happened while I was travelling with Rengoku. The basics of it were that Zenitsu and Inosuke who had fought at Natagumo Mountain had trained months at the Butterfly Mansion because of the potential that I saw in them. The Kamado children were quick to take a liking to both, and other than a few bumps in the road, their training went great.

Tanjiro was also quick to indulge me in what he had learned from Rengoku and the absolute hell that he went through while training under him. Laughing at his misfortune, we continue our conversation, building ourselves an atmosphere in which others couldn't intrude.

Finally, Tanjiro brought up the topic of Hinokami Kagura.

"Your blade color is a sign of the breathing form you're meant to master. If I've seen and heard correctly, the color of your blade is black. Just like that of the Yoriichi Tsugikun, the legendary Demon Slayer whose breathing art was the progenitor of Breathing Styles. Hinokami Kagura is the direct art of Sun Breathing. I would like to share more with you, but…"

"It's not safe! The demon may appear any moment now!" Breaking past our barrier with no effort, Rengoku informs Inosuke, Zenitsu, and Tanjiro of a very important fact.

Under Zenitsu's mental breakdown, the conductor walks in.

"Your… tickets… please..."

Rengoku and I both remain silent refusing to give our tickets while watching as Zenitsu, Inosuke, and Tanjiro give theirs. With their tickets stamped, it comes our turn.

"It appears that we have misplaced our tickets, would it be alright if you could come back to." I lie blatantly with Rengoku nodding his head in reassurance.

"I've already stamped… everyone else…"

"Well, that sure makes things simple for us."

Standing up, I grab the puncher and then crush it with my hand. Pulling the man forward, I chop him in the back of the neck, causing him to pass out. Safely placing him in an open seat, I turn to Rengoku.

"The Demon now probably won't come out now, so we have one of two options Rengoku."

Rengoku nods his head enthusiastically, "Alright then, let's sleep!"

Following Rengoku's blatant response I place myself comfortably back in a seat and, using the military breathing technique, letting me fall asleep in two minutes. Buying our bait even though Enmu knows who he has control over, I feel as five separate presences enter our train car.

Cracking one of my eyelids open, the five children make their way over to us, pulling out rope imbued with Demonic Energy. Shakily standing next to us, they go to wrap the rope around our arms, but Rengoku and I stand up, causing the five children to freeze in place.

"H-How are you awake?" One of them asks.

"He said everything would work out… so… how?"

Out of nowhere, one of the children rushes forward with a stake in her hand, trying to stab me.

"Don't get in our way! Because you guys came here, he won't let us dream!"

Acting in the same way, the other children also hold their stakes towards us.

"Apologies."

Hitting them in the back of the neck the same way I had the conductor, Rengoku wakes up Tanjiro and Inosuke while trying to wake up Zenitsu, however, I grab his hand and shake my head.

"He's better asleep, trust me."

---

"Huh, what happened?" Tanjiro asks, groggily waking up.

Instead of answering him, I give him the mask that I'd been gifted by Gyomei when I finished learning all the forms. Staring in confusion at the mask, I reassuredly place my hand on his shoulder.

"The only people who can handle the Demon that we're about to face are those who Enmu cannot look directly in the eye. I want you and Inosuke to deal with the head of this Demon while Rengoku, Zenitsu, and I protect the passengers. And just remember, if you're ever placed inside a dream like you just were, you need to cut your own neck to free yourself. Don't hesitate for a second, or you will be killed. Also, if the Demon ever happens to become a train, its neck should be the head car."

"This is a trial for you to go through Tanjiro!" Rengoku shouts. "Kill the Demon, and I'll congratulate you!"

Nodding his head in understanding, Tanjiro exits the train car and flips out onto the roof. Everything thereafter is left to Tanjiro. Explaining the situation to Inosuke as well and informing him to incapacitate the train operator when he gets to the front, he rushes through the train cars, not even bothering to go to the roof.

Standing patiently with Rengoku, the train then takes on an extremely grotesque texture and starts to emit bubbly tubes close to what I'd seen from Muzan. As the tubes start to grow from the train, I head to the back four carriages.

Pointing my sword forward, I activate my Demon Slayer Mark and my blade starts to emit its light blue aura. Using 'Total Concentration Breathing', I fly down the carriages, cutting a multitude of Enmu's flesh, making the train return to its natural state for a while until Enmu's flesh festers and regrows the patches I cut out.

Having my rhythm broken by a sudden piercing scream that came rumbling through the train, I easily fend off the weak tendrils that try and crush me. Continuing my defense, another scream then bursts out and an enumerable number of hands come from the flesh of Enmu.

Mincing each hand that appeared in all four train cars, the train then flies off the tracks, making it scrape dangerously against the rocky ground and cause all occupants of the train to rumble around.

With the death of Enmu, his Blood Demon Art begins to wear off and the train occupants begin to wake up, finding themselves injured and in different spots on the train.

As I go to help, a new demon's presence makes a shiver run up my spine.

Jumping out of one of the train's windows, I find myself looking at a tall and muscular young man with skin so fair, it appears bright, green-tinged white, decorated by a pattern of thick blue lines, which resemble criminal tattoos. The Demon has short, bright pink hair that fluffed out around his head, and inward-tilting yellow eyes with pink eyelashes and blue sclera that looked somewhat like cracked glass. The kanji for "Upper Rank" and "Three" are etched into his irises as well. The Demon wore little, only sporting a short, sleeveless dark purple pink haori that was cut off at his waist, left open to expose his chest. Below this, he sports a pair of baggy white pants that he rolled just below the knee with a blue rope belt to secure them at his waste. He also wears a chain of large round pink pearls around each of his ankles.

Crouched in front of Rengoku, I find myself staring at Akaza.