Before you start reading this story, I recommend you to read/watch/play both series first as to avoid any spoiler in this. I also recommend you to prepare a browser of some sort in case you find something or someone like the character you don't know and you have it to search for the knowledge.

Hyperdimension Neptunia belongs to Compile Heart, Idea Factory, and all responsibles for its working.

Kimetsu no Yaiba belongs to an author Koyoharu Gotouge and, to some extent, Shueisha and Ufotable.

Now then, with that all said, enjoy.

Tanjirou Kamado awoke to foreign hands shaking his body and jagged shapes pressing into his back.

Not exactly how he wanted to start the day, but he supposed that being able to wake up was a blessing.

After all, a Demon Slayer could only ask for so much.


A muffled voice that reached his ears made Tanjirou open his eyes, and he found a familiar face above him.

Long black hair that reached below a small waist, and black hair that ended in an orange shade at its tips. Soft, pale pink eyes softly looked into his own. To the average passerby, the sight would've been considered normal if not for the bamboo muzzle wrapped around an unseen jaw.

It was his younger sister who had been turned into a demon, Nezuko Kamado.


Seeing that her older brother had woken up, Nezuko backed away a little, allowing Tanjirou to get up and chase away his grogginess.

Tanjioru placed a hand to his head. There was no pain, but the boy noted the presence of a light dizziness.

He turned to look at his sister. "What's wrong, Nezuko? Did something happen?"

She continued to stare at him, before turning around to look around her.

Thoroughly confused, Tanjirou rubbed his eyes and mimicked his sister's actions.

Blue light. No sun. Stone.

His eyes widened, and he suddenly felt quite foolish for not noticing anything earlier.

Where am I?

As his eyes surveyed the area, his confusion only piled onto itself.

Are we… in a cavern of some sort?

No matter where he looked, all his eyes could find was earth. He and Nezuko were indeed inside a cave, or at least somewhere underground. However, what truly caught his attention were the rocks in every angle of wherever they were now.

…They were beautiful.

It was not the normal gray rocks, but shining blue stones, the likes of which Tanjirou had never seen before, decorated the otherwise dreary cave. Like stars, they seemed to twinkle in the cave's ceiling, further bathing the space in a blue light.

Tanjirou's mouth hung open in silent awe. To think that something like this could exist in the world…

And yet, the fantastical sight did nothing to ease his nerves. He was in an unfamiliar place. Not being on guard would be a death-wish.

How did I even end up in this place? Last thing I remember was…

He racked his brain to try to remember where he last was, or at least, the last thing he did, before he woke up here.

His face slowly scrunched up as he tried to remember.


Absolutely nothing. His brain came up with a complete blank.

His last memory was of the Butterfly Estate, and his recovery from the latest mission he went through with his companions and the Sound Hashira. But that couldn't be possible; the idea of being in a location one moment and waking up in a completely alien environment the next seemed too strange and illogical.

That is, unless he was closer to the Butterfly Estate than he originally thought. But he was quite sure that he would've heard of a cave with glowing blue rocks if that was the case.

Though, there was also the possibility that…

He pinched his cheeks. His body responded with the feeling of pressure.

Too realistic. If he could feel pain, dreaming was out of the question. He also dismissed the idea of kidnapping him easily because he couldn't remember any event that was worth capturing him or the things he had done to do so.

…Well, there's that time when it was revealed he was traveling around with a demon a.k.a. his sister to the Corps, but that's beside the point.

Right. So, suffice to say, he was utterly clueless as to the what, where, and why of his situation. But maybe Nezuko wasn't?

He looked to his left. "Nezuko, do you–?"

He stopped. No little sister in sight.

"Nezuko? Nezuko!?"

In a fit of panic, Tanjirou threw his head to his right, only for a feeling of relief to cascade over his being. Nezuko was poking at a yellow pile of something laying on the ground.

The thing, which Tanjirou realized to be a person as he steadily approached Nezuko, had yellow hair and a haori of the same color. Tanjirou gasped, and eyes gleamed with recognition.

His walk turned into a sprint. "Zenitsu!"

He frantically crouched down beside Nezuko and shook the boy's sleeping form.

"Zenitsu! Zenitsu, wake up!"

"Mhmm…" From Zenitsu Agatsuma's mouth came a low hum of discontent. "No more training… Lemme sleep more…"

Tanjirou's grip on his partner's shoulders tightened into a vice grip. "Zenitsu, this is serious! Get up already!"

"Fine, fine…!" With a groan, Zenitsu allowed himself to be pulled off the ground by Tanjirou and locked eyes with the boy. "What's wrong, Tanjirou…? I thought we were supposed to be resting. And why does my back–"

Tanjirou gently took hold of Zenitsu's head and turned it away from him.

"…Hurt?" Zenitsu's complaint died in his throat once he took in his surroundings. "Ah."

The moment of silence allowed Tanjirou a chance to let out a breath of air he didn't know he was holding. He cared about Zenitsu, he really did, but sometimes his tantrums could get grating.

Nezuko, however, hunched up and covered her ears. She'd traveled with Zenitsu long enough to know where this was going.

Really, it was no wonder she let out a groan of pity when her older brother only moved closer to the yellow boy. "Zenitsu? Are you oka–?"

"WHAT THE HELL?!" Zenitsu's scream echoed throughout the cave walls. "WHAT THE HELL EVEN IS THIS?!"

"Z-Zenitsu, not so loud!" Tanjirou winced back like he'd just heard something terrible, which he did, as far as he was concerned. His grip on the other boy's shoulder once again tightened. "You might attract something unwanted!"

Zenitsu's head snapped back to Tanjirou's, tears soaking the former's face. "Tanjirou, what's going on?! Where are we?! I don't recognize this place at all!" The green demon slayer let out a cry of surprise as his body was grabbed by the shoulder and shaken violently. "Answer me, Tanjirou!"

"That's what I want to know too!" Seriously, thought Tanjirou. When has this turned into an interrogation?! "I just woke up not long ago. I've got no idea where we are either!" He would've also added that he had woken up with Nezuko, but Zenitsu's violent treatment of his body did little to help him speak.

"What do you mean you don't know?! Are you telling me that someone kidnapped and threw us in this place?! Are demons attacking?! W-what if there's one nearby right now?! Wait…"

Tanjirou felt his body go still. "...Zenitsu?"

A moment of calm had allowed itself in the hurricane that was Zenitsu's wild ramblings.

…Only to be instantly destroyed as the yellow-haired boy screamed, "Did we die and wake up in hell?!"

And back came the shaking for Tanjirou. "Zenitsu, please calm down! You're not making any sense!"

"How can I calm down?! Maybe this is my punishment for being an unreliable waste of space! I'm doomed, Tanjirou! DOOMED!"


"Can ya both just shaddup?!"

A third voice pierced through the chaos, stopping them both.

Well, mentally hummed Tanjirou. At least we're all together now…

The two boys turned, and sure enough, there stood a half-naked man dressed only in baggy hakama pants. Brown fur wrapped around his hips, and black fur down his legs and feet. The lack of shirt left his muscular upper body naked for the world. The boar mask, which would freak out any ordinary person, in fact reassured the demon slayers. It had become something of a trademark for the boy in front of them and they both knew how important it was for him and how he would get when he was without it.

"Inosuke!" Tanjirou beamed, happy to see his other partner.

Inosuke Hashibira approached with a stomp in his step. "You two interrupted my sleep with your noisy screaming! I could feel this whole place fill up with your crying!" Exhale steamed out from large pig nostrils, and his gaze locked onto Zenitsu. "Especially you, Monitsu."

"I have the right to do so!" Zenitsu yelled back as he frantically gestured at the area around him. "Is that pig head stopping you from seeing where we are?! If it is, I'll have you know it's creepy, weird, and probably demon infested! If you can't even see how lost we are, I don't wanna hear you get mad at me!"

"That doesn't mean you get to scream your head off and ruin my sleep!"

"Stop it, both of you!" Tanjirou marched between the bickering slayers and raised his hands. Honestly, these two really were a handful.

His tired eyes briefly met Nezuko, who had been passively observing the ordeal.

The girl met her brother's eyes and shook her head. The message between siblings went unspoken.

You're on your own, too sleepy.

Tanjirou let a quiet sigh escape his lips. Indeed, a Demon Slayer could only ask for so much.

It took Tanjirou a little bit of effort, but Zenitsu and Inosuke had finally listened to him and all of them (including Nezuko) were gathering around, pondering their situation.

"So?" Inosuke was the first one to break the silence. "Where are we?"

Tanjirou shook his head. "I believe I can speak for all of us that we don't know exactly where we are, but it's clear that we're in some sort of cave."

"Not just any cave." chimed Zenitsu as he took in the surroundings with his eyes. "A cave with crystals… or at least, I think they are."


"Those bright rocks," The yellow-haired boy pointed to one of the many luminous blue rocks. "Are called crystals. They grow deep underground and fetch a hefty sum in markets. I've personally only heard about them, but I never got the chance to directly see them. U-until now, of course."

"I see…" Zenitsu's knowledge of the world never failed to amaze Tanjirou. He was glad he could call him his friend.

Tanjirou took another look at the cave once more. Now that they had calmed down, he could finally observe this place with more detail.

The more he looked, the more he felt that the cave was, without a doubt, really beautiful and breathtaking, probably due to these crystals he now knew brightening the whole area. Even watching one of the crystals itself was quite idyllic to stare at.

And it seemed that Nezuko also felt the same thing with how her eyes were sparkling when looking at it.

When he finished admiring, he turned his head back to address his partners, "Well, wherever we are, it will do no good if we stay here and do nothing. The first thing to do is to get out of wherever we are and then we can try to sort things out of our situation." As much as beautiful this place was, it didn't change the fact that they were still in an unfamiliar place, one that could be very much dangerous and unsafe if they stayed here for any longer.

While Zenitsu agreed immediately to his suggestion, Inosuke crossed his arms. "Why? This place doesn't seem half bad."

"What do you mean 'Why?'" Zenitsu glared at the boar-masked boy. "Do you want to live here, is that what you mean? Well excuse me, but I'd rather leave this cave for good and find some sunlight."

"He is right, Inosuke." Tanjirou nodded at the yellow boy. "Besides, do you two notice it?"

Zenitsu raised his eyebrows. "Notice what?"

"That we're not the only one here."

Thanks to his enhanced smell, Tanjirou could easily tell that there were other living beings residing in this cave. However, the scents were not that of a human, nor was it a demon like his sister that he had grown used to.

At the same time however, the scents that assaulted his nose greatly perplexed him.

There were few that he expected for creatures that originally belong in the underground like bats and some insects, but that's nothing compared to the ones with mystifying scents.

He could smell the unmistakable scent of flesh most living things had, but the scent of blood, which he was all too familiar with, was much weaker. Instead, in place of it was something that Tanjirou could only describe as strange. The best comparison he could make was the smell of ozone that clung to power lines in the city. But even then, the two scents were too different to be called alike.

The boy found himself at a loss as to what exactly he was smelling. But what the scent meant was very clear.

Something lurked in this cave. Something that was most certainly not normal.

"Ha! I've long known about it even before you pointed that out." Whereas Tanjirou relied on his sense of smell, Inosuke's sense of touch was so extraordinary he could feel even the small vibrations in the air and from afar. That's how he knew there were others besides themselves.

"I see… I was hoping I was just imagining it when I heard those noises…" Like the other two, Zenitsu also had his own incredible sense that concentrated on his heightened hearing, allowing him to hear even the farthest sound. He could even hear someone's heartbeat without having to put his ear to one's chest as long as he was nearby enough to hear it.

"Well," Tanjirou turned his head to look ahead at the path that led to other areas. "I suppose it's time for us to explore and find our way out. The sooner we leave, the better."

"I'm with you completely, but there is something that has been bothering me. Where's our sword?"

Tanjirou widened his eyes after hearing Zenitsu's question. He didn't realize until now that his Nichirin sword was nowhere on his waist.

Luckily, he felt a tug on his haori before he could start panicking.

His gaze was on Nezuko as she was the one who did it. "What's the matter, Nezuko?"

She answered him by pointing in one direction.

When he looked at where she was pointing at, there, he could see not only his sword lying on the ground but also the large wooden box made by his teacher and cultivator, Sakonji Urokodaki, for the purpose of carrying his sister during daylight and hiding her from the sunlight. His friends' Nichirin sword(s) were also there.

Quickly, he ran to retrieve his sword and the box, followed by the other two.

Holding the sheath in his left hand, he pulled the sword out with his right hand and inspected it to see if it was in good condition.

No scratch on the surface, no nick on the edge, and didn't feel rusty on his black-colored Nichirin katana. It almost looked like he received a new one, something that puzzled Tanjirou since he had been using it a lot in the past and was on the verge of breaking it… again. Whatever the reason, he would not complain about it anyway.

Once he was satisfied with his inspection, he sighed in relief as he sheathed it back, putting it beside his left waist. "Was afraid that we had to go unarmed, now we don't have to worry about being unprepared."

"Eh," Inosuke shrugged, his chipped dual Nichirin swords now on his both waist. "If it's not demons, I can fight without 'em. My fists will be more than enough weapon to deal with anything."

"I hope you don't use that on people." mumbled Zenitsu, also done inspecting his lightning streaks-patterned Nichirin sword.

Carrying the wooden box on his back, Tanjirou turned to the others. "I guess we are all ready. How about you two?"

Zenitsu and Inosuke nodded, set to go.

Looking at his side, Nezuko also nodded, as if she understood him.

With a determined expression, Tanjirou declared, "Let's go."

And so, they took off, marking their first journey in this unknown world.

As the three Demon Slayers and one demon went through their way in finding the exit, Tanjirou took notes of something at the back of his head.

As he suspected, he encountered the creatures where the mystifying scents originated from and they were clearly not friendly if the hostile feelings he got from them were true.

What he did not expect was what these creatures were like.

The first one being what looked like a ghost that you could physically harm, which should be impossible given what Tanjirou knew of them. When they first saw it, Zenitsu shrieked aloud. Thankfully he did not faint and they managed to get rid of it quite easily. What surprised them was it disappeared into nothingness after defeating it; kinda similar to demons once their head got decapitated with a Nichirin sword or when their skin got exposed under the sun for too long.

The second was a small, blue blob-shaped creature with a dog face and ears. Honestly, Tanjirou would find it cute if weren't for the fact that it had the same bad aura as the others. It was also slimy to the point he and his fellow Demon Slayers had to put a little power in their swing for a clean cut. In Nezuko's case, she clawed them with ease, though the remains of them dirtying her kimono after their death made her feel displeasure.

More and more of these strange creatures were keep coming at them, be it a ghost, slime, or new types, yet the four of them keep moving on, although it would be more accurate to say that Inosuke rushed through the front, slashing all the way when the creatures got close, with Tanjirou, Nezuko, and Zenitsu following him from behind.

It was relatively easier dealing with them than when dealing with demons, but the ridiculous amount of them was really troublesome to the point the boys had to unleash a few of their breathing techniques here and there.

Speaking of breathing, that was also the other thing Tanjirou needed to point out.

When he executed the Third Form of Water Breathing to dance his way while killing the creatures at the same time, water literally came out from his sword.

Ever since the beginning when he became a Demon Slayer, every time he used a Water Breathing form, he would visually think of manipulating the water that accompanied his every swing, but that's exactly it; he imagined it in his own eyes and mind. And he was pretty sure the other Demon Slayers were also doing similar imaginations like him with their own style of breathing.

So he was pleasantly surprised about this contrivance as this was never happening before. Now, for every attack he made as he breathed Water Breathing style, water would visibly appear that his sister and friends could even see it. The same could be said for the others too; Zenitsu's Thunder Breathing thunderous fast strikes, Inosuke's Beast Breathing wild slashes, and Nezuko's flames that she ignited from her blood.

Actually, her Blood Demon Art was already visible to the naked eye even before this revelation; it was also the same with the other demons he met.

Despite this however, he and his friends could still perform their breathing attacks normally, just adding the apparent effect. And the latter was exactly it; he noted that the water was not real by any means but rather a visual effect that coated his sword and it stopped appearing when he stopped using the technique. Yet for a visual effect, he could feel the realness and the cool sensation from it, as if it really was the actual water he brought out.

…Hmm, he wondered if he could manifest a fire if he used Hinokami Kagura…

Back to the present, they tore every monster (they decided to call it that) and kept going straight for what seemed like a long time. A few times they would find a dead end and had to turn around to go another way.

They soon found a tunnel that led to another part of the cave, however there was no single crystal ahead, making it almost devoid of light.

Zenitsu, being a scaredy cat, didn't want to go there and said they should find another way, but Inosuke paid him no heed, running instantly into the dark tunnel. No other choice, they followed him, much to Zenitsu's protest.

It was only for a short period of time but as they kept running, they could see natural sunlight coming from the other side a few meters away, indicating that they were almost out of this cave.

It also meant that it was noon outside, so Tanjirou had to make a quick stop to secure his sister into the box before resuming their run.

At long last, they made it to the exit and stepped out, feeling the heat of the sun washing over them.

"Phew… we did it. We're finally out." Tanjirou panted. While he wasn't overly exhausted, running while also dealing with those monsters had definitely tired him out.

"Thank goodness… I thought we'd never see the sun again." Letting out a sigh of relief, Zenitsu allowed himself to fall on his butt, feeling the grass.

"Hmph," Inosuke crossed his arms. "Those weird critters weren't even worth the effort. It was too easy."

Zenitsu's content face swapped to a scowl. "That's what you're concerned about, you pigheaded idiot!?"

"Who you calling pigheaded, Bakamitsu?!"

"You're the pi– wait, did you just call me a fool!?"

"Enough!" shouted Tanjirou. "There are more pressing matters at hand. Until we find a safe place, we can't afford to lose focus."

The de-facto leader of the group turned his attention away from his companions and surveyed his surroundings.

Green plants, blue skies, and… mushrooms of different colors? Tanjirou questioned. And is that metal I'm seeing?

The trees and greenery indicated that they were in a forest, that much he was sure of, but the scene they were greeted with was peculiar. Strange metallic rings wrapped around and jutted from tree trunks. Thin rivers of water unnaturally sparkled under the gentle sunlight. Above one of these rivers was what Tanjirou assumed to be a bridge, with architecture that was unlike anything he had ever seen before. Just what part of the world had he and his friends found themselves in?

Tanjirou shook his head. He needed to stay focused and had to find out where they were. No need to confuse himself over why everything looked so strange, not unless it helped them get home.

Like he had done so many other times in his life, he took a deep breath through his nose.

…And was disheartened to find out something more concerning.

The air here… why is it very different?

In his life before and after becoming a Demon Slayer, Tanjirou had an excellent sense of smell, and had memorized every scent he came across. Humans, objects, animals, demons, none of it was alien to him. All it took was a breath through his nose to know what would be in store for him.

But this air… it was… well, it didn't feel like anything he was most accustomed to. Of course, the scent of air varied from place to place. The cleanliness of the mountains contrasted heavily with the grime and smog of the city.

But it wasn't the air's scent that was the problem, so much as it was its texture. It was the way it felt against his nose and tickled his nostrils that signaled to him that something was horribly wrong.

He had noticed this characteristic of the air back in the cave, but didn't think much of it at the time. He chalked it up to the crystals and later strange monsters being the ones responsible. After all, he'd never encountered either.

But now, he was away from the cave, away from the monsters, so why was the air still different?

Tanjirou's lips quivered. A-are we even in Japan anymore?

To possibly be so far away from home… the idea brought him no ease.


A quiet voice had promptly pulled the boy out of his dark thoughts. He'd not aware someone was coming up to his side.

Turning to face Zenitsu, he heard him mutter softly, "Are you alright? You were spacing out there."

"Ah…" Tanjirou shook his head, smiling. "Sorry, I was just… thinking."

"About what?"

"About our current predicament."

"Oh. Right, of course." Nodding in understanding, Zenitsu's features hardened ever so slightly. "Maybe we could find a town? All the metal here is disconcerting, but everything should make sense if we can just find civilization."

"Mhm, you are correct." Tanjirou let out a noise of affirmation, then focused his gaze onto a bridge up ahead. It seemed like a good place to start. "Stay close, everyone. I doubt we've seen the last of those monsters from the cave."

"Yeah, the last thing I want is to get separated..." In a flash, Zenitsu's face soured, and he turned around. "And will you stop banging yourself against that tree!?"

Tanjirou could only laugh sheepishly as he watched his other partner ram his head into a tree.

After prying Inosuke off of the tree ("It looked at me funny, I swear it did!"), the trio had found themselves about to cross the bridge.

"Hmm?" Inosuke stopped in his tracks.

Tanjirou glanced back at him. "Is something wrong, Inosuke?"

His simple response was to point in a left direction.

There was a hole, about as wide as a tree, which laid at the riverside.

Large, thought Tanjiro. Too large to be natural.

"And?" Zenitsu asked back. "It's just a hole in the ground. Are you going to point at everything you see?"

Inosuke frowned behind his mask and let out a huff of mild frustration. "Shut it, Rokutsu. That hole's fresh, and it ain't normal either. Whoever made it put a lotta force into the ground."

"Well," Tanjirou looked for a bit longer before turning right. "Whatever that hole is, it's none of our concern." He took a step forward. "Let's keep going."

With that, they crossed the bridge and resumed their trek through the woods.

"Nee, Tanjirou…"


For the second time in one day, Zenitsu screamed from his soul. "WHAT THE HELL IS THIS PLACE?!"

Tanjirou couldn't bring himself to reprimand his friend's outburst. The feeling of shock was mutual.

The reason behind the state they were in now?

Civilization. Or what appeared to be civilization. Tanjirou couldn't find any other word to describe their current location.

He at first thought it to be a city, and this much seemed to be the case, what with all the people walking about.

But cities didn't have buildings made of shiny metal, cities didn't have trains in the air that were held up by lines which also seemed to defy gravity, and cities certainly didn't have towers that nearly pierced the clouds!

Zenitsu swore that he would've fainted right then and there, if not for the numerous blues and whites which gave the scene before him some semblance of order. Even for a city boy like him, this was way beyond anything he had ever seen; this place made Tokyo look like a mud hut, for Kami sake!

It was as if they were looking hundreds of years into the future, and a hundred more years into something completely unrecognizable.

Zenitsu, who had since transitioned from terror to awe and back to terror, made himself smaller and smaller as he hid behind Tanjirou.

Inosuke's head looked left, then right, left, then right again, and he continued this frantic motion several more times.

Tanjirou didn't fare any better. His eyes were glued onto the tower at the heart of the city.

The more he stared at it, the more his breathing went rigid. His arms and legs trembled, and buckets of sweat poured down his face. His vision blurred into a mess of colors.

Before anything got worse, the hanafuda-earrings boy quickly shut his eyes.

Calm down, Tanjirou! Calm down! Get your breathing back under control and don't panic!

He inhaled, then exhaled.

He inhaled, then exhaled again.





Once he maintained the Constant breathing technique, his body relaxed considerably.

His vision regained focus, and with gusto as he could muster, he called out to his fellow Demon Slayers, "Zenitsu, Inosuke, you guys are fine?"

"E-Eh!?" Zenitsu gawked at him incredulously. "Tanjirou! This…! This…!" Unable to form words, he started pulling at his hair. "Gyaah! My mind is too jumbled right now!"

"Zenitsu, please listen to me first…!" Tanjirou tried to reason with him, but to no avail.

The yellow-haired boy broke. "Just what the hell is happening to us?! First the cave, then the monsters, then–!" His bloodshot eyes looked down at his shaking hands. "Is this even real!? I don't want this to be real! Please wake up wake up wake up wake up wake up wake–"


A sound of slapping resonated around them, but weak enough that only the trio could hear it.

Tanjirou retracted his hand back to his side, relieved that the power he put behind his slap was low to avoid any serious injury. "Do you feel better now?"

"Y-Yeah…" Zenjitsu lifted a hand to his cheek. "...Somewhat."

Tanjirou's lips curled upward. "Good." Then he frowned. "Fear is a natural reaction, I understand that, but I don't want you to lose yourself in it."

Zenitsu could only nod in response.

"You should've just punched him, Ponjirou. Might actually get him to stop whining for good."

Tanjirou whirled around to the voice behind him, completely missing the glare Zenitsu aimed at Inosuke whom Tanjirou was facing now. "Inosuke, you..." The older Kamado prepared to fire back with a reprimand, but found his indignation changing to confusion when he noticed the demeanor of his other friend. "...You're awfully calm about all this."

"Hm?" Inosuke tilted his head. The motion would've been endearing, if not for his visage. "Nah, I'm the same as you guys. My heart's jumpin' around my chest and shit. Why's it matter though?"

"It matters because… because of EVERYTHING, you moron!" rebutted Zenitsu, pushing Tanjirou aside. "This place is… I don't even know what this is! But it isn't normal, so stop acting so relaxed!"

"Well…I don't care." Steam blew out from his boar head's nostrils. "'Cause I'm gonna trample this whole place flat and make the people here acknowledge the mightiness of the King of the Mountains, Inosuke Hashibira!"

"No, you are NOT going to do that! You'd either end up making a fool of yourself or getting euthanized!"

"Ewdinice? Wazat, a food?"

"Why you…!"

Tanjirou chuckled and allowed himself to smile. Wistfully, he wondered when Zenitsu and Inosuke's bantering became an anchor to reality for him.

…Probably when trees started having metal in them.

He clapped his hands, getting both of their attention.

"Zenitsu, Inosuke," He started, "This place does look a bit like a city, doesn't it? Especially with all the people here." Said people had grown into a small crowd that looked on at the trio from a distance. They seemed perturbed, if a bit curious, though their gazes mostly directed to the pig-headed boy. "That cave we ended up in after waking up, those weird creatures we have never seen before, the metal forest, and now… this." He gestured to the blue-and-white city skyline. "All of this is so unreal. It feels like we're so far from home…"

He felt his whole being become drained when he said the last part. He wanted to deny it so much, he really did, but the probability of them being nowhere remotely near Japan was disappointingly high, and he was struggling not to fall into despair on the spot.

But that wouldn't do. He needed to keep his weakness from showing up in this distress moment. Not at all he would break down here.

"We have problems, and I think this place can provide us with answers." He faced the road that seemed to lead deeper into the city. "Let's ask around. Hopefully the people here can indulge us with some information."

"Tanjirou, a-are you sure?" Zenitsu nervously chattered out. "It's not that I oppose you, but…"

"Zenitsu, it'll be alright." Tanjirou mustered the best smile he could. "After all, we have each other, so as long as we don't get separated, none of us will be alone."

The thunder breather's gaze lingered on him for a few moments. He shut his eyes… and sighed.

"Okay. I understand." Zenitsu firmly nodded. "I'll… do my best. Yeah."

The two looked to Inosuke, who had, since his previous outburst, remained still.

Tanjirou smelled sweat. Zenitsu heard the erratic thumping of a heartbeat.

"Inosuke…" Tanjirou took a step forward. "Are you–?"

All of a sudden the beast breather pumped his fist to his chest. "Don't you worry, Tanjirou! Just believe in your boss, and everything'll turn out fine! My minions are off-limits after all!" The self-proclaimed boss whipped his head back and aggressively pointed at the trio's growing audience. "YA HEAR THAT WEAKLINGS!? LOOK OUT FOR LORD INOSUKE!"

Inosuke's wild exclamation washed through the crowd of onlookers like a blast of water. Quiet mutterings of confusion and fright sounded from the people as the peanut gallery finally dispersed.

Tanjirou sweatdropped. "A-Ah, thank you, Inosuke…?"

"Yes, your worship of me is appreciated!" Inosuke stomped his way past Tanjirou and onto the road in front of them. "Now let's go! This place ain't gonna pulverize itself!"

Zenitsu let out a sharp cry of frustration and ran after him. "You pigheaded simpleton! We're gonna ask questions, not show off your stupidity!"

Tanjirou let out a noise of exasperation. He took it back. 'Anchor to reality' was not an accurate statement to describe their bickering.

"Stupid!? Wanna prove that with your fist!?"

"That's not how it works, but I might just take you up on that!"

Tanjirou grabbed their heads and mashed them together, leaving them in their stun as he walked ahead.

Many hours had long since passed since the Demon Slayer gang first began searching for answers to their current situation.

It was after they visited many parts of the city and talked to some people that they finally got their answers. Yet instead of feeling pleased and satisfied, conflicted was all they felt in their heart as their situation became worse.

To be fair, their reaction made total sense, and anyone who knew the greater context of their debacle would expect them to feel this way. After all…

They were no longer in Japan. Or in any country outside Japan.

They're now in a world completely different from their own.

A whole new world. One that they still didn't have any slight idea how they got here.

Now Tanjirou understood why the air was so indescribably different since the moment he woke up in that cave, because this was not the air of the world he was familiar with, rather this was this world's air. That being said, there was not much of a difference if he had to be honest; it was still similarly the same as his world's air, but for someone with a very sharp sense of smell like him, he could easily tell the nuance of it.

Morbidly emboldened by the truth of their circumstances, they pressed on for more information.

This world, known as Gamindustri, had four major landmasses.

No, not just any ordinary landmass, because to their shock, the land that they were standing on right now was actually a freaking floating island!

…Tanjirou wondered if the reason why the air was different was if it's because of the world itself, or because they were so high up in the sky since he knew the air would gradually lessen if you climb up to the higher ground like the peak of the mountain, although that did not seem to be the case as the air here had the same usual amount as on the lower ground.

Anyway, each landmass housed a nation with each of them having a theme of its own.

Lastation, the Land of Black Regality.

Lowee, the Land of White Serenity.

Leanbox, the Land of Green Pastures.

And lastly Planeptune, the Land of Purple Progress, the very land they were in now.

That wasn't the end of it; apparently each of these four nations was governed by a ruler of sorts, who protected the land from monsters and led the people.

These rulers went by the name and title of CPU, and when the boys asked who these CPU were, another shock befell them once more.

CPUs, as in Console Patron Units, were otherwise known as goddesses.

Not goddesses or gods who the people prayed to and left offerings for at old, decaying shrines, but real goddesses of flesh and blood who commanded their worshippers and walked amongst them.

As one would easily guess, each nation had a respective goddess living in their land.

Black Heart of Lastation, White Heart of Lowee, Green Heart of Leanbox, and Purple Heart of Planeptune.

"...Heart? What kind of silly name is that…?" Zenitsu couldn't help but bluntly criticize this world's goddesses. "I mean… colors? Seriously?"

His answer was an elbow jab to his side, courtesy of Tanjirou.

Continuing on, since they were now in Planeptune, there was a likely potential that they'd see the goddess of this city, Purple Heart. However, that potential became low when they overheard she had disappeared for many years and hadn't returned yet.

When asked about her, they got many diverse responses. Some said she ran away from her responsibility, while others said she was residing in a land called Celestia; a realm above the human world where the goddesses came from. In between these responses, they heard something about 'a war beyond the sky', which caused the boys to go tense briefly due to the word 'war', but soon regained quickly while dismissing it as someone making it up. At any rate though, it did not seem like Purple Heart would make her reappearance anytime soon.

The trio kept on learning all about the world of Gamindustri as much as they could in this advanced city. They were so caught up that when the sun was already set and replaced by the stars and moon, they realized there was another problem they forgot to mention.

They had no place to stay.

Zenitsu proposed they should find an equivalent of an inn to rest in, but Tanjirou dismissed that idea immediately because they had no money and he doubted the people here would accept yen as payment.

With no other choice and a reluctant agreement from Zenitsu, they decided to settle on one of many not-too-tall buildings' more accessible rooftops. Ideally they should have gone to someplace else that was at least better than the rooftop, but they absolutely didn't want to take a risk of being spotted slumbering in the open area and accused as 'vagabonds', as Zenitsu put it. This was why they decided to sleep in a place with less chance of people snooping on them. Regardless, the cold night and rough floor shouldn't be too much of a challenge for them.

For Tanjirou, the cold didn't affect him much as he used a little of Hinokami Kagura breathing technique regularly to warm his body.

Inosuke also didn't seem like he's having trouble with it, no doubt due to the fact he spent most of his life in the wilderness mountains.

Zenitsu… not so much if his not-so-quiet complaints was any proof.

Despite all that, ultimately they got a good rest after a long stressful first day in this new world… as good as they could get.

In the next morning, the trio formulated on what course of action they should take now.

Obviously they still needed to find out how to get home, but until then, they needed to find a way in order to survive while they were here, that included how to obtain money.

When Inosuke told them they should get money in a… illegal way, he got glares from the two and they rejected it straight away.

It wasn't until a minute later that Zenitsu remembered something, then proceeded to tell them about a certain place he'd heard from the citizens during their walk yesterday.

A place where you could take miscellaneous quests and receive rewards upon completing them; The Guild.

With that decided, the trio descended by jumping down to an alleyway where there were no people to scare off unintentionally (Inosuke felt idle stares from the two aiming at him for reasons he didn't understand) and made their way to the Guild with the help of directions.

Fast forward, they arrived at the Guild, marveled at the ins and outs of the building, learned how it works, and needed to register to make a Guild card that served as a personal identification for each of them before they could take a quest.

The process of making these cards was utterly fascinating and not difficult. All they had to do was to 'scan' their palms and let technology do its work. Then the clerk behind the counter (she let out a scream when she first mistook Inosuke as a monster because of his mask) asked them who they were and her fingers moved so fast as she 'typed' to fill in their IDs.

Once they got their card, the clerk explained that they were currently in the lowest ranking, so they only could accept quests that were suited for beginners. As they completed more quests, their ranks would increase and in turn they could take up harder quests with greater rewards.

Inosuke grumbled why they couldn't just take the harder one even with their current rank, with Tanjirou replied to him that it was to ensure people's safety and to gauge based on one's experience.

If this was anything like the Demon Slayer Ranks, then it wouldn't be different to say their rank would climb if they completed a variety of quests.

All that said and done, the trio were now ready to pick a quest. Or quests since apparently you could pick more than one quests.

There were many types of quests that were provided, but the most common were what was called Hunt and Find.

Hunt, as the name implied, was a type of quest to go and hunt down monsters, mostly extermination. Some of them were usually detailed to kill a specific monster that the client requested.

Find was to search and, well, find particular items the client asked you to. The items were arranged from simple mundane things like herbs and plants to a certain body part of a monster. The latter could be obtained by defeating monsters and sometimes they'd drop what's called a drop item.

Lately however, there had been a lot of Hunt quests. The reason according to the clerk was, following the time of the sudden disappearance of the Planeptune's goddess, monsters began appearing more than usual and were nearing the city's border. With no protection from the purple goddess, the people had to rely on adventurers and the military to get rid of them.

The trio didn't have any problem with these kinds of quests; if anything, it's convenient for them. It wasn't so dissimilar with the missions they got back home and they could use this opportunity to explore more of the world they'd found themselves in.

They took some time in picking their first quest until they eventually settled on one.

To exterminate monsters known as Shampurus that frequently pop up in a place called Zeca Ruins. Like others, these creatures had begun to spawn drastically, adding more danger to Planeptune.

After asking the clerk about the location and was later given a printed sketch of a map leading to the ruins (the clerk was surprised how passe these newcomers for not knowing about GPS and not owning a device), they left the city and headed off to its whereabouts.

On their way, they came across a river and took a short break to catch some fish when they remembered they hadn't eaten anything since yesterday.

It's a good thing the fish didn't disappear when it died, or else we'd have to do the quest on an empty stomach. Tanjirou prayed in silence before munching the freshly skewered fish he had caught; he'd already sniffed it for anything poisonous. It tastes good. Maybe I should cut it into sashimi.

At a distance away, he saw Zenitsu dipped his head into the river then he pulled out, gasping. "Ah… Fresh water. How I miss you."

"Oi, Kentarou, Tonkotsu!" Inosuke came up to them with his swords held high, three fishes impaled by each of his blades. "I just caught another of these bunches!"

"Please don't eat too much. We're still in the middle of our trip." Zenitsu deadpanned at the pig-headed boy while Tanjirou just chuckled.

Their short break's over, the three of them resumed their journey.

They ran into a few monsters on their way, including the blue slimes with a dog face which were now identified as Doggos they'd learned back in the Guild, but they quickly dispatched them with no difficulty.

How can something so small and cute be this aggressive and dangerous? thought Tanjirou, hacking the last of Doggos.

"I swear, the people here call it Doggo because of how it looks, not that I'd not agree with them." Zenitsu spoke as he sheathed his katana. There was a slight tremble, but he held it on. "Compared to the demons we fought, this feels like a mockery to our hellish training for how less threatening and, might I add, annoying these are, don't you agree, Tanjirou?"

"Who knows," The hanafuda-earrings boy shrugged. "But if what they said about the sudden increase of these creatures is true, then it would cause a lot of problems to the people that don't have any means to protect themselves." He surveyed around him once more before walking forward. "So far we have only found the small monsters, but there's no telling that the bigger ones do not exist around this world."

"Then I hope we'll find the big one." Inosuke grunted. "These lame excuses of mutts didn't make me break a sweat."

"...You know, I'm starting to wish we don't find one at all."

"Did you say somethin', Nakutsu?"


The sun was already high up in the sky by the time they almost reached their destination.

Finally, they arrived at Zeca Ruins, standing before the entrance.

"Here we are." Tanjirou silently awed as his eyes went to the wall of the ruins, looking at its structure. "This is my first time I've been in a place like this. Don't think I will find something similar back in Japan."

"Yeah, kinda like straight from a storybook." Zenitsu agreed, analyzing the ruins also. "Looks ancient too. I wonder if this was supposed to be a temple before it became what it is called now, or perhaps it's already like this since its early development."

Inosuke hummed while pondering aloud, "This ain't bad at all. Might use this place as my stronghold once I gather hundreds of my minions."

"You better not, or do you want us to leave you here? Also do not forget why we're here to begin with."

As they entered, Tanjirou's nose twitched.

There are monsters here. Must be the Shampurus.

They wasted no time traversing the whole area, intending to get their quest done.

Soon enough, they ran into a Shampuru.

"So…" Zenitsu pointed his finger at it. "That's a Shampuru?"

"I think so, yeah." nodded Tanjirou.

"The one that looks like a rabbit and has whiskers?"


"The one that is also tiny and small like every other monster?"

"…I believed I had mentioned the possibility of big monsters during our walk before arriving here, but… yes."





Suddenly the yellow-haired boy threw his head up and shouted loudly, "WHY MUST EVERY MONSTER WE'VE COME ACROSS HAVE TO BE SO RIDICULOUS?!"

His shout alerted the Shampuru of the trio's presents. Unfortunately that's not the end as they saw more Shampurus appear from every corner, all with hostile aura.

Inosuke whistled. "Calling all of 'em so we won't have to search around the area. Impressive."

"Oh shut up! I didn't mean to!"

They drew their katanas simultaneously as they silently assessed their enemies surrounding them.

"They were not kidding about the numbers." Tanjirou observed the enemies. "There are at least dozens of these Shampurus."

"Doesn't matter how many there are, I'll tear apart every one of these rabbits!" Inosuke gripped his blades tightly, ready to pounce anytime.

"Somebody seems to be excited to do the slaughtering." Despite his ever-obvious nervousness, Zenitsu thanked in the back of his mind that these rabbit-looking creatures did not make him scared enough to faint. The same applied to almost all monsters they'd encountered so far as they all were still tolerable for him, unlike the demons.

Taking a stance, Tanjirou said, "Well, we should probably make this quick, though be careful still. Small as they may be, I can tell they are ferocious." And he didn't want to get bitten by those sharp teeth these rabbits were showing.

The Shampurus, sensing the readiness from their prey, charged at them.

In retaliation, the boys as one moved, then breathed.

"Beast Breathing, Fifth Fang: Crazy Cutting!"

"Thunder Breathing, First Form: Thunderclap and Flash!"

"Water Breathing, Fourth Form: Striking Tide!"

They attacked, defended, and backed up each other in swift as they slashed every single enemy in front of them.

They weren't having a hard time dealing with the Shampurus like any monsters they had met so far, although they noted that some of these Shampurus had a tough skin and were more ferocious than the others. In the end though, they managed to handle it just fine.

Moments later, they walked out from the ruins, still in one piece and undamaged, except Zenitsu who was lifting his right arm, a hole evident on the sleeve of his orange haori.

"It's okay, Zenitsu. We can find a clothing shop to fix it once we return to the city." reassured Tanjirou.

"...If only I did not trip myself." sniffed Zenitsu, his head replayed the scene when he misfortunately fell onto the ground and one of the Shampurus took that opening to bite into his arm. Luckily he pulled back before that so no bleeding, but it successfully tore apart the cloth. "I mustn't be careless next time."

The trip back to Planeptune was uneventful, save from another Doggos attack and a few other small-type creatures. Before they knew it, they had arrived.

Tanjirou turned to his friends. "Let's report back to the Guild, then afterward we will go to a shop where they can fix Zenitsu's haori."

"Don't forget to find an inn later. I don't want to sleep outside ever again."

"All that hunting with those weakling monsters makes me hungry. I wanna eat some food!"

"Alright, I get it, okay? Now, come on."

Upon reaching the Guild, they told the clerk of their completed mission and received credits–the currency of this world–as the reward.

For the rest of the day, using the money they had earned, they went to the clothing shop to fix the yellow boy's haori, which they had to leave it behind until it became good as new, and then ate at one of the small restaurants. Inosuke whined that he couldn't eat more than a fair portion before Zenitsu told him they needed to save their money until they earned more. They also used their remaining time to understand more about Gamindustri and Planeptune besides what they already knew.

When it was dark, they found an inn–or specifically a hotel–where they could finally have a comfortable rest in a pleasant room. It was a cheap one they could afford, yet the interior design inside the room still made them awestruck. There were two beds, an L-shaped couch, a black rectangular hanging on the wall known as a television, and a bathroom.

As someone who was born in Taisho Era when modernity hadn't reached a peak yet, it was of no surprise that they played around the room with feisty curiosity. Sometimes they tried any technological thing they could find in the room with full astonishment on their face, and sometimes Tanjirou and Zenitsu had to hold back Inosuke from trying to destroy anything lest they got kicked out by the inn's owner for breaking a property.

Tiredness eventually came into them, so they prepared to hit the hay and turned in for the day. Zenitsu was the first to sleep on one of the beds, followed by Inosuke on the couch, snorting loudly.

Tanjirou, the last one still awake, was wordlessly gazing at the moon that shone brightly through the window, overlooking Planeptune City.

So far, he and the other two had a basic understanding regarding this world–the law, rule, system, culture, common sense, everything–and adapted relatively well (even though naturally they needed to learn more, especially the wonders of technology here), so they wouldn't have to worry about totally lost and ignorant to everything.

Yet, in spite of that…

We still don't know how to get back to our world.

The more he thought about his homeworld, the more Tanjirou felt hopeless.

Hopeless like when he failed to save the people he knew, including his family and Kyojuro Rengoku, the late Flame Hashira.

Hopeless like when he didn't have enough power to prevent tragedies that the demons caused to innocent people.

But this one, hopeless because he might be stuck here forever, leaving the rest of the Demon Slayer Corps members to deal with the demons that were still ravaging his homeland.

The feeling of despair was creeping back at him, slowly clenching his soul as he had no idea what he should do in this adversity.

"Set your heart ablaze."

A sudden flashback had effectively burned away any despair he was having in his heart.

He instinctively reached in for his pocket then pulled back as his hand grabbed an object, holding it in front of him.

A guard, shaped like a flame with red-colored on the core and orange on the border.

A guard Senjuro Rengoku gave to him.

A guard belonged to Kyojuro Rengoku.

He closed his eyes, recalling the Hashira's last message.

To not let yourself get crushed in the face of impossibility.

To not stop, for time wouldn't wait and aid him.

To not give up.

He gripped the guard tighter as he opened his eyes, now seemingly flaring with fervor in them.

That's right. I mustn't let the sense of hopelessness get into me. If I– no, if we give up early, then everything would be over before we even tried anything.

With that conviction, he held his head high and set his gaze forward, his heart burning with resolute and unwavering.

Until he went through everything thoroughly in this world, he wouldn't give up in finding his way to return home, no matter what.

Thank you, Rengoku-san. I'll continue to do my best.

Whatever gratitude he would give had to be halted as a hand on his shoulder snapped him out from his thoughts.

Looking to his side, he saw Nezuko staring at him.

"Nezuko? You're awake?" Looking across her, the wooden box he put near his bed was opened wide.

Nezuko didn't give a verbal answer, not that he expected her to. But the way her pink eyes looked at him showed that she was concerned.

Noticing this, he ruffled his sister's hair. "Sorry if I made you worry. A lot of things have happened while you were asleep." He gazed at the moon again. "Like how we are far away from Japan now."

Nezuko kept quiet, remaining to listen to what her brother had to say.

"I'm worried that our sudden disappearance may cause a problem for everyone." He thought back to the inhabitants of Butterfly Mansion. "Sumi-chan, Kiyo-chan, Naho-chan, and Aoi-san must be concerned about us. Kanao and Shinobu-san too."

Tanjirou could easily picture every single one of them panicking about their whereabouts, especially the three small girls. While he rarely saw Kanao let out a lot of emotions through her face, he could easily imagine and bet that she must be also worried about them deep down.

"Me, Zenitsu, and Inosuke are doing our best to keep on what we can do now in this different world. And hopefully… we can return back to where we should be. There must be some way that could help us out. After all, we still have our responsibility and duty to protect every human from any merciless demon."

He felt something touching his shoulder. Turning his head, he saw Nezuko had inched closer and resting her head on it.

"Mmm." Was all she could say.

This elicited a warm smile from the older brother. "Thank you, Nezuko."

He's not alone in this.

Zenitsu and Inosuke were with him to support each other's backs and carry their struggles together.

But most importantly, Nezuko would always be by his side, wherever he went.

Whatever awaits them in the future, Tanjirou believed everything would be alright. He's sure of it.

The siblings remained staring at the moon for a moment, before they eventually decided to retire.

Thank you for reading the first chapter.

How is it? I do hope I nailed everything in this one. While there might be some flaws and mistakes, I'm actually quite proud of it.

Due to my current study, I'm a slow writer, and whether I will continue to update this depends on my motivation, so I do hope that motivation will keep staying within me. If not, then I'll refill it by dumping every content of both series to my face, revisiting what I'd played/watched included.

Well, guess that's all, so I bid you a good day.

P.S.: To the old readers, if you've come back to this chapter, then yes, I've finally revised it. Noticed the glaringly differences? With this, I can finally focus on the next chapter, but this is not the end of this revision. In the future, there may be another change in this first chapter. Be sure to look out for it.

I couldn't have done this much without my newest Co-Writer DietGingerAle. Thank you so much.

Oh, that doesn't mean I'm closing off anyone who would like to join in our working; the offer still applies. If you feel like it, contact me personally. And if you're wondering, no, no Discord server yet; not enough members yet to make one.