Disclaimer:

I do not own nor claim all the rights to 鬼滅の刃 | Kimetsu no Yaiba | Demon Slayer; all rights are reserved to its respective creator, Koyoharu Gotōge. This is purely a work of fiction; names, characters, businesses, events, localities, and occurrences are all extrapolated from the author's writings and imagination or utilized in a fictitious manner. As such, any direct or indirect references to actual entities, dead or alive, or events do not, in any shape or form, resemble the opinions of the author.

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"..." = Dialogue

'...' = Internal monologues

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Hey guys, just wanted you to know that this chapter is pretty short and that I might've rushed it a bit.

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The whistling wind—though not too overtly loud—evoked an oblique remark to the tension present within the atmosphere of this particular day. It was a testament to both the uncertainty that lay ahead along with the apprehension prevalent throughout the city milieu. 

Although it was roughly midday, the ambiance within the vicinity of this particular time of day—one that anyone would postulate to be conducive to an uplifting tone—was subjected to degradation; the consecutive cases of missing persons in conjunction with the widespread disclosure of corpses whose identities are congruent to that of the aforementioned absentees engendered a unanimous sense of dread and deprivation that permeated throughout the heart and focus of the city's denizens.

Though the day had reached its zenith, the gleam of the sunlight was incandescently radiating its glimmering rays in a fulgurating manner upon the Earth as if the capacity to execute the full potential of its enormous power was critically hindered. The proper rationale for this odd phenomenon would be the presence of the copious amount of clouds situated in an azure—yet, simultaneously colorless in soul and spirit—atmosphere; each of which occluded the luminary features espoused by the nearby star. 

Thus, the environment was neither morbid nor was it brimming with gaiety and optimism; the correct terminology would be more along with the line of a vague or subtle interpretation of pessimism. 

A ubiquitous, unyielding sensation of negative emotions circulated the propinquity while imbuing a pernicious undertone to the growing metropolis; however, one shouldn't be quick to attribute such fervors to the hitherto persons to which their fate either remains unknown or discerned under unfavorable circumstances. 

For, in these turbulent times of change and capricious events to which the Taisho Era—arguably either exacerbating or amplifying—had somewhat inherited from Emperor Meiji, the traditional-heavy people of Japan are not yet attenuated to such drastic reforms to the rudimentary facets of their lives, economy, and society. 

Therefore, it is to be expected that a member of the agricultural peasantry is not prone to the adjustment that is envisaged in a setting analogous to a rapidly industrializing economy. Ergo why it is important for one to make that clear distinction; for the tendency of many to ascribe the infinite woes of modern society upon an abstract notion of a single thing or being harboring all the great evil is a propensity harbored and denoted by a great many.

Nonetheless, whether such inclinations are inherent in the congregated human psyche or whether such rationale procures an unhealthy basis at the expense of the people's intellectual functionalities within the framework of a mercurial society is a notion within the boundaries of a philosophical debate; hence, why the denoted topics are essentially irrelevant in the context of this predicament. 

Such woes exacted upon the port city of Yokohama are ones that are indeed originating from a supernatural source—a demon, to be specific. Therefore, while it is true that the temperamental nature of an adapting and industrializing society does play a major role in the perfidious mentality of the given ambiance, the very presence of such great evil is propitious to the provided conjecture of a nefarious demon inflicting upon iniquitous acts of terror and bloodshed to which the Hashiras are to properly address in due time.

..

..

..

..

While the ingress was indeed relatively short in height, the lateral pipe which it permitted entry into didn't harbor synonymous characteristics with regards to its apotheosis as the entrance did. The immediate entryway was a metallic tunnel in which the adjacent walls constituted what was left of this tattered, old pipeline. 

Upon entering, the Hashiras concurrently noticed that the temperature had overseen a noticeable drop, but not too precipitous of a reduction to promote freezing temperatures or to obstruct the acclimated slayers from their contemporary, stationary conditions. 

Moreover, while the aperture that embodies the physical configurations of the entrance did provide countenance with regards to vision through what little sunlight could possibly transfer its photons over into the tunnel, the passage remained caliginous and almost impossible to distinguish its idiosyncratic, tangible components due to the lack of natural light. 

Even so, the slayers paid no heed and partook in a continuous hike into the cavern to which the darkness lay. 

The synergy between the perpetual darkness and the crisp, numbing breeze that occasionally sought to traverse the elongated pipeline brought forth an aura that was both ambiguous—in the backdrop of a vague setting—combined with ambivalent indecisiveness as to whether fear, malice, or curiosity should reign supreme within these metallic corridors.

It wasn't exactly a wide tunnel, to say the least, as the length from one wall to the opposite was approximately 6 feet (1.8 meters) which thence induced the slayers to walk in a single-file line. Giyuu, who set foot in first, was logically first in line while Shinobu was right behind.

"It's getting quite dark," Shinobu points out as—the further they delved deep into the passageway—the dim light slowly underwent its premature demise

"Hm," Giyuu simply replies in his monotone voice.

"Try not to aimlessly walk straight into a wall, Tomioka-san," Shinobu says impishly.

"... I'll do my best," he replies.

"Oh my, did I just hear Tomioka-san admitting that he has a penchant for being clumsy?" Shinobu mocks.

"I said nothing of the sort," Giyuu promptly counters.

"It would indeed be a shame if you actually did embarrass yourself like that," she teases.

"I highly doubt the occurrence of the sort," said Giyuu.

"Oh? Is that so...? You should realize that it is getting darker in here," Shinobu insinuates.

"I'm not going to stroll around into a wall," Giyuu rebuked.

"I'll take your words for it~," Shinobu said mischievously.

They continued their trek across the conduit, making note of the precarious disposition to which they find themselves in; as it may enable a lethal ambush from an unidentified enemy. Therefore, both kept their guard up despite the supposed equanimity present in their outward appearance—which is upheld by their comported demeanor.

After a minute of walking, it was plainly obvious that the lack of natural light had incurred upon a situation in which the ability to fully execute a comprehensive observation of the surrounding purlieu had been effectively nullified. As a result, the Hashiras were essentially blinded and unable to fully utilize one of their five fundamental bodily senses to survey and surmise from the contents of their surroundings.

"Watch your step Tomioka-san, you might suddenly trip and fall," Shinobu takes a jab at her partner.

"The same goes for you," Giyuu responds.

"Though, I am surprised," said Shinobu.

"Surprised?" Giyuu questions.

"Hai, I did not anticipate this lateral pipe to be lengthy," Shinobu answers.

"Indeed, though I believe there should be an end to this soon enough," said Giyuu.

"True, this old apparatus shouldn't be too extensive to perpetuate this sort of situation," Shinobu opined with her eclectic knowledge, "Meiji-era infrastructure wasn't exactly comprehensive, to put it mildly."

"I am also impressed that a demon—if there is one around here—could fit through this constricted tunnel; given that a majority aren't exactly slender with regards to physique," Shinobu adds.

"As we discussed earlier—before making our way into this pipeline—there's always the possibility that not all demons harbor identical musculature or physical traits," Giyuu expounds.

"That's also true," Shinobu concurred.

"I see light," Giyuu suddenly spoke.

"Huh? Really?" Shinobu, unaware of the ongoing developments due to the petite constitution of her somatic appearance, asks for clarification.

"Yeah, it's not much, but I am confident that we are approaching an exit of some sort," Giyuu answers.

"Good to hear, though it's been roughly 5 minutes since we entered the lateral pipe..." Shinobu notes.

"..."

"You walk too slow," Shinobu admonished.

"I beg to differ," Giyuu replied.

"Oh kami-sama, if only Tomioka-san walked a little faster from his turtle speed, we might've completed the mission by then," Shinobu continued to annoy the Water Hashira.

"That doesn't make any logical sen— "

"Such is the tragedy of the Insect Hashira, forever subjected to the torture of trying to bring some sense to the Water Pillar," Shinobu exuded a histrionic tone as she attempted to further irritate Giyuu.

"Kocho-san, I exercised caution in light of your suggestions not to undergo a major fumble due to my lack of vision. And yet, here you are now complaining about how slow I am. So, which is it: too fast or too slow?" Giyuu said with an exasperated expression.

"Oh, I don't know, maybe both!" Shinobu exclaimed.

"Not a plausible answer," Giyuu chastised.

"But an answer nonetheless~," Shinobu counters.

At this point in the conversation, there was enough light emitting from the other end of the tunnel to authorize the full usage of eyesight to perceive the circumambient outline within the vicinity.

"It's easier to see," Giyuu states.

"Thank you for pointing out the obvious," Shinobu replies.

"... I'm not wrong though."

"Tomioka-san, the validity of your statement is irrelevant. What is important, though, is your lack of common sense to realize the fact I'm also aware of this new development."

"... Right..." said Giyuu.

'Highly doubt he caught any of that; after all, he is a certified social hermit,' Shinobu internally notes.

Eventually, within a reasonable time period, the two Pillars had reached their coveted destination: the exit.

However, upon entering the foyer-like antechamber, it seemed as if all the characteristics that pertained to the preceding environs—straitened, crepuscular, odious, and so on—underwent a substantial alteration that converted the atmosphere, ambiance, and physical arrangement of the room's multi-faceted array of configurations into some else entirely. 

For one, the drop in temperature was almost immediately reversed as the two stepped foot into the chamber; with the chilly climate that encompassed the antecedent passage completely revamped into a more suitable, tepid temperature that was neither too warm to facilitate sweat nor too cool for one to doubt the supposed warmth of the contiguity. Moreover, unlike the cold, decrepit undercurrent that was palpable within the lateral pipeline, this new locality procured a more lively, corrigible setting in which the tension from the previous passageway was diluted to a more sustainable and acceptable level. 

The ambiance was indeed more simple, yet so cohesive in the sense that amalgamated aspects of what was lacking in the outside world—soothing, serene emotions—had cohered to orchestrate a haven for such placated sentiments.

Abstract notions aside, the room was a visually, enthralling sight that harbored riveting traits in order to draw the attention of any given observer. 

There existed a mini-reservoir in the circumcenter of this cavern, complete with freshwater, lush greenery, and some living organisms whose habitat constitutes the entirety of this picturesque cave within the confines of the Earth. 

The water emanated a strange luminosity of a combination of light green and light blue; cyan blue, to be exact. The water was—of course—translucent, but the reflective nature of this little pond expounded a visually fascinating feature of this cave; the undulating component of water movement was reciprocated onto the reflection to which it is synonymous with—in other words, the water's shadow was quick to requite the movement and project thereof onto the rocky and rugged walls of the grotto. 

Such a visual scenery effectuated a scenario in which one would expect to occur in a natatorium, but, alas, this is a natural occurrence and not one artificially contrived by human beings. It was an alluring sight, almost as if one had entered an entirely different world due to the sheer discrepancy between the tunnel and the cavern. 

The only source of natural light, it would appear, originated from within the pool itself. As a result, the room was engrossed with the illumination of a greenish-bluish radiance that engulfed the entirety of the vicinity. 

Furthermore, the presence of the luscious green plants—that, with the exception to a large concentration around the reservoir, were distributed quite evenly throughout the room—amplified the effects of such coloring upon the rest of the cave.

It was a most extraordinary observation to the Pillars—one that would enrapture anyone as a matter of fact. Therefore, the two simply stood there, gawking at such beauty unbeknownst to man which laid beneath one of the biggest cities in Japan; a fact one shouldn't take lightly.

"Oh my, well this is surprising," Shinobu broke the silence.

"Yes..." Giyuu simply replied as he himself was enchanted by the charm and appeal of this wonderful scene.

"Who would've thought that such natural beauty was directly below the feet of over a million denizens..." Shinobu said emphatically, "Never have I encountered something like this before."

"Neither have I... but we have a mission to complete. It's best if we go on our way now," Giyuu began walking; he was the first to be released from the spell.

"And to think that a demon lives down here, this place alone almost convinced me that it couldn't be possible," Shinobu followed.

"Demons reside wherever it's convenient for them, so it wouldn't be a surprise to think that something down here is advantageous to that demon; something that motivates it to remain here in this specific area," Giyuu comments.

"Possibly, but I suppose we'll figure out if we get the chance to interrogate the enemy—which is unlikely to happen when it's dying," said Shinobu.

As the slayers made their way to the opposite end of the grotto, they arrived at the crossroads of two passageways; either take a left or right turn.

"Well, looks like we're going to have to choose between the two, Tomioka-san," Shinobu stated.

"Maybe we can investigate for any clues—footsteps, fingerprints—to conduct an accurate postulation," Giyuu propounded.

"Or, we could split up. But I'm sure that will make you feel lonely, so I'll disregard it," Shinobu proposes.

"... Is it possible for the two of us to part ways?" Giyuu inquires.

A vein protruded from Shinobu's forehead, "Tomioka-san, that was a joke. Don't take it too seriously. Besides, protocol dictates that we are to remain together under these circumstances."

"Oh... right..." Giyuu realizes.

"Impressive, looks like you've completely forgotten what the rules entail in the first place," Shinobu said merrily.

"I haven't referred to regulations for an extended period of time now, so I suppose I've forgotten the minor details regarding team dynamics," Giyuu explained.

"Probably because you either partnered up with me or, for the most part, no one at all!" Shinobu exclaimed.

"I don't need to be reminded of that," Giyuu gave out a grimace of irritation.

"Why? Because no one talks to you??" Shinobu ridicules.

"More along the lines of me having to put up with the likes of you," Giyuu retorts.

"... Are you asking me to chop off your hand, Tomioka-san?" Shinobu said almost politely.

"I don't believe so," he replies.

"Do you want to argue over this again?" Shinobu says as she attempts to maintain her composure.

"I'd rather not," said Giyuu.

"Thought so," Shinobu let out a small sigh.

However, she then subsequently chuckled.

"Hm?" Giyuu, astounded by this sudden outburst, questions.

"Oh, I'm sorry hehe... I was just reminded of how our mission so far has mostly been banter, misunderstandings, and awfully embarrassing situations. I just found all that a little humorous," Shinobu smiled.

"Well... I'm glad you do," Giyuu simply responded.

'Even if he's stupid at times, I do have to admire how blunt he is...'

"Alright then, shall we make a choice?" Shinobu suggests.

"Indeed," he answered, "I think we should follow the path to our left."

"Oh? And why's that?" Shinobu queries.

"Because due to the absence of any clues on our right, I surmised that the path to our left is the best choice," Giyuu explains.

"Why left? What clues lead to such a conclusion?"

"The circumjacent rocks that surround the right entrance are mostly jagged and seemingly unadulterated, but the passage to our left seems to be somewhat artificial due to the lack of protrusions on the surface of the surrounding rocks," he provides his rationale.

"Ah, I see," Shinobu comments as she examines the observations provided by Giyuu.

"Left?"

"Left."

The entrance's apotheosis in terms of height wasn't as extensive as the antechamber, but it was tall enough to permit the entry of two human slayers. Thus, the two continued their journey deep into the darkness.

As they were walking, the calm, soothing atmosphere and milieu of the luscious, green reservoir had all but dissipated; all to be replaced by the same morose and somber that could simultaneously be attributed to a starless night sky or a cloudy day without raindrops to entice one's own mind and spirit. It was, essentially, a reversal back into the conditions prevalent within the metallic conduit; a depreciation in almost all aspects, as one could say.

After a few minutes of silence, Shinobu spoke: "Do you feel scared, Tomioka-san?"

"What a foolish question," said Giyuu.

"I take that as a 'yes'," Shinobu grinned.

"Hardly would be," Giyuu replied.

"Or maybe you're too shy to say it!" Shinobu said excitedly as if she had an epiphany.

"Not at all."

"Don't worry Tomioka-san, I'll protect you from the demons," Shinobu teases.

"I don't need protecting."

"Everyone has someone to protect them, and I'm sure you do too," Shinobu points out.

Giyuu gave it a thought before he quietly replied, "Unfortunately for you, I don't."

Shinobu, taken a little aback by this response, came to understand the underlying implications of this exchange of words.

"Don't worry... You're not the only one..." Shinobu said with a dull tone—one that seemed forced.

Giyuu merely stared at her with curiosity and bewilderment, 'Her bond with her sister was indeed a strong one... I shouldn't pry into this matter.'

"I see... In that case, we can turn to each other," he suggests.

"Huh?"

"Since there isn't anyone else, I thought it would be convenient to look towards one another in times of required assistance. Since we have been consigned together on numerous occasions, I have learned a great deal about you and can remain at ease in your presence. At least for me, talking to you will suffice my desire for social contact," Giyuu explains in a very sincere demeanor.

"T-Thanks, I appreciate it," Shinobu, a little flustered after hearing all that, somewhat stumbles through her words.

'I hate it when I get unnerved like this around him... It's always around HIM. Why him of all people? Why do I find him so fascinating and enticing?' Shinobu begins to question herself.

"Hey Tomioka-san— " Shinobu started.

Suddenly, Giyuu ascended his right arm to not just interrupt Shinobu but also halt her current advance forward.

"Tomioka-san?"

"... Tripwire," a look of concern furrowed onto Giyuu's face.

"Tripwire? What do you mean?" Shinobu examined the ground in front of her, only to find exactly what Giyuu was describing.

A thin, silver wire stretched across from one side of the tunnel to the other.

"A tripwire? How can this be possible? Did a demon set up a trap of this sort? Or was it humans?" Shinobu bombards the colloquy with a plethora of questions.

"I don't know. I've never come across a situation in which the enemy intentionally utilized manmade material and conventional stratagems to set up a trap of this sort. Usually, demons would have their own means of attaining such goals, but not in this case..." Giyuu touched on the subject of such abnormalities.

"This either means that the demon we're dealing with is willing to use human-like behaviors and propensities to further its own goal, or this is all just a coincidence because some people—for whatever reason—set these up on an undisclosed basis," Shinobu summarizes.

"Why would someone set this up down here then?" Giyuu questions.

"A question we may never be able to answer, should that indeed be the case," said Shinobu.

"Either way—whether it be people or demons—the likelihood remains far too low for us to draw up any conclusion with confidence," Giyuu speculated.

"I agree, but I believe it's best if we disable and extirpate this artifice as soon as possible," Shinobu proposed.

"Let's look for the source of the stimulus; there might be a mechanism that will trigger in light of a force pressed upon the wiring," said Giyuu.

"Maybe it activates a trap door of some sort, or maybe a fatal explosive."

"We'll figure it out."

Squeak

The Hashiras heard what seemed to be a pusillanimous cry from the ceiling. Both instantaneously were on guard, as it is common for their foes to initiate surprise attacks at any given angle or orientation. However, the origin of this peculiar peep was finally pinpointed when the very source of that sound dropped from the brick ceiling and onto the ground. It was a brown rat.

"Oh, it's only a rat," stated the Insect Hashira.

"We are in a sewage system after all," Giyuu added.

"Well then, back to business," Shinobu plainly stated.

Giyuu, on the verge of reverting back to his prerogatives due to his consentient opinion concerning Shinobu's remarks, noticed something off. He observed the rat, then he observed the tripwire. The rat, as it was initially attempting to climb back up to the ceiling via the walls, would fail to succeed in that area; compelling it to find an alternative pathway to its desired destination.

Unfortunately for everyone—Giyuu, Shinobu, and the rat itself—the rodent ascertained that the most expedient avenue of approaching its dilemma was to walk straight through the tripwire...

"Kocho-san, the rat," Giyuu called out.

"Huh? What about it?" Shinobu turns around to face her interlocutor.

"Kocho-san get back!" Giyuu yelled as he abruptly pushed Shinobu away from the locus of the supposed troubling event.

The rodent fractured its head as it came into contact with the alloy that comprised the contents of the metallic wiring.

BOOM

The trap had been triggered into effect.

The Earth shattered as the detonation of the incendiary device produced a force of epic proportions. A strong wind was formulated as the exertion of incredible strength—powered by the energy of the discharge—thrust the full brunt of fulmination that ripped through the atmosphere like a lightning bolt. 

The surrounding texture that defined the wide array of rocks, rusting metal, and organic complexes were hastily unfastened from their respective disposition as the awesome power of the fulgurating-like exercise of force prompted the removal of such substances as means to uncontrollably refurbish the locality. 

From an area that was at relative peace with itself and the surrounding environment, to one begrimed with dirt and its image sullied by the sudden and violent ruckus exacted upon the visage. 

The thundering and sonorous explosion castigated the aura of the solitary, confined space from that which elucidated a mellow atmosphere to one which released every imaginable outburst of energy possible in order to wrought upon the Pillars a screeching noise that twisted and corrupted the ambiance once and for all. 

The smooth surface that hitherto defined the tunnel's configurations was immediately corroded and refurnished with a corrugated texture that utterly permuted the various shapes and sizes of the cave's idiosyncratic features. 

Moreover, debris permeated throughout the expanse of the room as the natural soil, pieces of manmade objects, and more items dispersed and circumscribed through the available space.

Shinobu, who had little to no time to comprehend the situation as it occurred, was swiftly jerked backward as an insurmountable force pressed against her body, throwing her off the ground and sent flying at an enormous speed towards a randomly-selected direction. And not even until she could recollect her thoughts and take steps to remedy this predicament did her physical incarnation smash right into a metal pipe, knocking her out almost indefinitely.

Giyuu, who had the miserable luck of being situated closer to the site of the eruption, was sent airborne. However, unlike Shinobu, there wasn't a structure strong enough to halt the projectile that carried corresponding characteristics to Giyuu himself. Thus, instead of undergoing a painful landing on a given composition of resilient materials, Giyuu's back disintegrated a brick wall before falling down into an unknown chasm that was complete with wooden pillars and planks that he excruciatingly tore through during his descent downwards—all without the consideration of his volition. 

Then, before he could recuperate and seek to rectify this conundrum, he landed on a sloped metal pipe and rolled downwards in the direction of the incline. 

As he incorrigibly slid down, his body blew through another brick wall into smithereens. Until finally, he was no longer situated on the ramp. 

However, to the contempt of his mind and body, he landed in a stream of cold water which utilized its current to draw Giyuu away from his antecedent position. 

All the while, his physical status experienced repeated beatings and agonizing pain while his mental state completely ceased to properly function; and thus terminated all cognizant functionalities in light of the exacerbation of the physical condition.

Neither Hashiras were conscious nor did they find themselves in a favorable state of affairs.

It was a major setback indeed...