THE COLOR OF THE WORLD

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Disclaimer: Kimetsu no Yaiba belongs to Koyoharu Gotouge

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Genre(s): Adventure/ Hurt/Comfort

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Warning(s): Typo is my most loyal fan, spelling mistakes because English is not my mother language, Possibly OOC and a lot of Angst. I hope. Not Beta.

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Manga: Chapter 4 & 5

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There are a few hundred members of the demon slayer corps. The organization isn't officially recognized by the government. But it has existed since of old and still hunts demons today. However, the identity of the leader of the demon slayer corps is shrouded in mystery.

Demons. Staple food: humans. They kill humans and eat them. It is unclear when or where they first appear. They have impressive physical abilities and their wounds heal quickly. They can reconnect severed flesh and grow new limbs. Some demons can change form. Others possess strange powers. The only ways to kill them are by exposing them to sunlight or by cutting off their heads with special swords.

The demon slayer corps fight demons face to face. They are human, so their wounds heal slowly and lost limbs do not return. Nonetheless, they fight demons in order to protect ordinary people.

"I am a trainer," Nezuko stood with back straight, listening to Sakonji's tale in bated breath. They're back in the mountain again, now with full stomach and energy. Her face was covered by bandages—Tanjiro threatened her not to pull it off before it heals completely or she's going to face his disappointing look, his widening eyes silently said. Even though Nezuko could feel the said injuries were already long gone by now. All of it is mostly scratches, but she humors him anyway. He was just trying to baby her like the usual older sibling. Really warm her heart—however, that doesn't mean their training will be halted just because of that. So here they were, surrounded by fog just like yesterday and thin air just like yesterday also, "as it sounds, I train swordsmen. There are many trainers. In different places, they use various training methods."

"In order to join the demon slaying corps, you must survive the final selection at mount Fujikasane," he continued, "I decide whether you may attempt final selection or not."

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Nezuko stomped into the house, passing the calmly-drinking-tea Sakonji and pulled the happily-eating-mochi Tanjiro, who squawked in startlement, to the back room; he could see her pouting and not wanting to look at the old man straight in the eyes.

She's been doing this since the start of their training; getting beat up by the trap, coming back home black and blue, and proceed to dump all of her frustration to her brother. Sakonji didn't want to intrude, but sometimes she was just too caught up with her story-telling that she didn't realize she cranked the volume of her voice up before her brother shushed her. It was funny and, dare he say, endearing. However, they will see the smile on his face when they managed to force his mask out of its place. And that means, never!

"...can you believe him, urgh!"

What a feisty girl He chuckled.

"First he upped the traps. Not only rock but knives and pits full of swords," Nezuko waved her arms around, more in frustration rather than trying to describe the whole ordeal in more clarity, "sure, my Sight has been getting better because of that. The fog I saw is a lot clearer and the speed of their appearance is increasing; rather than flying like a feather, maybe you could say they're flying like a ball being kick with full force. Something like that..."

"Doesn't mean I'm happy with the way he taught the lesson!" she pouted when she saw her brother nodding, agreeing. Half in Sakonji's brutal way of teaching—it may be dangerous, but the results of it are clearly showing—and half in Nezuko's safety—he's still fussing over her whenever she's back with cut and bruises, "I'm convinced he's trying to kill me for good."

"And after that, he ordered me to do the whole thing but now with katana on my side," she continued, "it really gets in the way! I've been caught in a lot of traps that I was sure I can dodge if I don't have that thing lugging around and hindering me!"

Tanjiro tilted his head and let out a hum, she nodded, "I know. I've to get used to it because that's my number one weapon and protection from the evil demon. Do you think I can ask for a lighter sword, though? Maybe later after I passed the test..."

"Oh, I also started swinging the sword around," she opened her hand and showed the blistered palm to her brother, "he taught me that katana breaks easily. It's strong against force lengthwise but weak against forces from the side. With a katana, I have to attack straight ahead. The direction of the blade and the direction of the force I apply must be exactly the same. That's why I've been training on how to handle the weapon correctly. Because hear this, he said he'll break me if I break the sword! So mean, so cruel! Niichan, he's just as cold as the mountain!"

The burgundy-haired boy laughed, Nezuko whined.

"Today I did nothing but fall down. Training to break my fall and get up quickly..." as Tanjiro continue munching on the food while the sister told him her daily activities, she couldn't help but stare. After the first disaster of the trap-evading test, Sakonji ordered them to sit down. Nezuko was too tired to eat supper so most of the meals went into her brother's stomach. She didn't think too much at that moment. However, she realized the old man had been eyeing the oldest with a strange look—she guessed, as she couldn't really see his face and could only judge from the body language. The second oldest sibling let out a questioning grunt, he turned to her.

"You know why man-eating demons are called man-eating demons, right?" he asked, in which Nezuko reluctantly nodded, "then don't you think it's weird that your brother is eating human food right now?"

Her sleepy countenance instantly disappeared, now jolted awake. She swiveled to the figure of her demon brother, orbs widening. Sakonji was right, it is weird. Doesn't mean she wants Tanjiro to start eating human now, but that doesn't mean this situation is not confusing them anyway.

"And I saw him giving a prayer to the previous victims at the temple too."

"Oh, I think he learned that one from when I'm...burying my family," Nezuko answered, holding back a choked sob she got whenever she talked about her passing mother and siblings.

The old man gave an affirmative hum and scratched his chin in thought, "maybe your wish to turn your brother back to human is not just a pipe dream..."

"Huh?"

"It's clear that he regained his energy from eating our food instead of consuming human flesh. And he can learn new things from observing other people act. You can say that he's like a toddler, mimicking everything he sees," he reached out and mess the already messy hair of Tanjiro. The said person was not bothered by it and just keep eating, "if you ignore the fangs and eyes, or his inability to stand under the sun, your brother is just like a normal person. This is only my theory but I think...the human side of your brother is more prominent than the demon side."

"Keep showing him the examples of what's right and what's wrong, I'm sure with that, we can retain his humanity as long as possible and the chance of curing him will be a lot higher," the old man mumbled. Nezuko thought a bit of affection leaked from his usually strict tone. Sakonji's wrinkled hand are still patting her sibling's head and she couldn't shake the feeling of deep melancholy wafting from his being (his fog flew oh so slowly. The usual current of raging ocean now turned calm and almost soothing), fond at whatever he was seeing from her brother; the past he wanted to forget yet cannot because that is what shaped Sakonji as who he was, "honestly. This is truly a miracle."

"No matter what happens, big brother will always be big brother, huh."

No matter that he's turned into a demon and lost almost his entire memories, Tanjiro will always be there to protect you.

Nezuko cried right there and then. And, as much as she wanted to placate her brother that she was okay, she couldn't. She was just too happy. Too relief. His appearance may have changed.

But he is still her precious brother nonetheless.

She woke up from her flashback when something tapped her thigh. Tanjiro was looking at her, head tilted and brows scrunched. Look like when she was busy recalling 'that night revelation', she stopped recounting her hellish exercise sponsored by the old man in tengu mask. Nezuko shook her head and smiled, "oh no, I'm okay. Just a bit tired. Where was I? Oh yes, training. So I wield my sword and face Urokodaki-san, who was unarmed, with the intent to strike—hey, don't look at me like that! His fault for not holding back! Besides, he's ridiculously strong! He kept flipping me down to the ground like a sack of potatoes, the nerve of him!"

"I have nothing more to teach you," he said, as his way of opening today's lesson.

For the past few days, they've been practicing breathing and some standards form as the base of water technique he had been wanting to teach her. Sakonji was super strict at that lesson, always hitting her stomach whenever she did something wrong and said that that was because she didn't have enough strength in her core. Nezuko was glad she didn't vomit in retaliation with how much and how hard he smacked it; though she didn't mind if she did, serve him right.

Although he'll add another punishment for the insolence. Never mind then.

"H-huh?" the black-haired girl blinked, still trying to control her breathing

It's been a year since they arrived at mount Sagiri. And that was all he said after bringing her to another place that has different fog and different density of air.

Her last lesson...was to split the boulder with the katana he lent it to her.

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Wait, what?

"Wait a minute, Urokodaki-sa...aand he's gone," Nezuko glared at the boulder Sakonji told her to break; the thing was taller than her, taller than the old man himself even. It was tied by a rope as thick as her two arms. It needs four, maybe five, adult hugging the boulder to describe how wide this natural occurrence is. And she hadn't even mentioned its mass or weight. Can this thing even be split? With a katana that, if you compared it sideways, was as big as a toothpick? The blade would definitely break!

Since that day, Sakonji hasn't taught her anything, no matter how much she bugged him for it.

The only thing she could do, besides wracking her brain how to slice that boulder, was practicing what the old man had taught her every day. Holding her breath, flexibility, the most basic thing.

Yet no matter what she did, Nezuko still cannot split the boulder. Half a year had passed, the times keep flowing, the earth keeps rotating. Tanjiro's still a demon and he keeps worrying over her working schedule. She knew he knew her smile started straining, worry started planted deep within his heart. And Nezuko hated herself sometimes, how her brother lose sleep over her—although he didn't really need to sleep and went to bed just because. Maybe some kind of an unconscious habit from when he was still a human?—but she was so frustrated. Clearly, it's not enough. She hasn't had enough training. She has to do more, more, more—

What if it's...because I'm no good?

What if all of this is useless? Will niichan stay like that forever? Will niichan cannot regain his memories anymore? Will niichan never experience the warm, warm, warm day of spring? The breezy day of fall? The heat of summer? And can only experience the cold, cold, cold night of darkness like winter without end?

I have no answer! Nezuko leaned on the boulder, tears started springing out of her eyelids. I'm losing hope! I'm going to fail!

"Fight, Nezuko, fight!" she smacked her forehead to the stone, not caring how the rough texture hurt her. At least it had woken her from her depressing thought, "you have to do it! For the sake of niichan, you have to do it!"

"My, my, how miserable you look~"

Nezuko jolted, she immediately leaped back and ready her stance; not anticipating someone other than her to be in this mountain. A girl was sitting on top of the boulder. Her hair is black and kinda spiky, it reached her shoulder. She's wearing a red, flower-pattern short kimono and a fox mask concealed her face; it has the same flower decoration on the right cheek, but blue in contrast.

W-Where did she come from? The second sibling of Kamado was wary. I can't see her color. A fox mask?

"You should not grouch and grumble," she could hear her pouting, "that's not how a lady should act, see?"

The girl stood up, and went to the edge of the boulder—

The air shifted—

Nezuko gasped, she put her sword upward—

WHAAKK

And managed to block her spinning kick at the very last second.

Unfortunately, though, she didn't consider her to use the other leg somehow. And because of that carelessness, the girl—who was definitely younger than her, judging by how short she was—tripped her and sent her spiraling to the ground.

"Aww, you're so slow," the girl giggled. It may just be Nezuko's imagination, but her aura suddenly intensified. Her cute fox mask turned intimidating and the harmless kid now feel like a predator in hunting, "if you keep this up, you'll never be a demon slayer, you know~"

Nezuko, still on the ground, stared in befuddlement, "w-who are you? Where are you come from?"

The girl didn't answer. Instead, she cocked her head to the side, disappear from her sight, and appeared at her right eyesight; spinning kick was halfway done.

The second Kamado's sibling immediately ducked and rolled, managing to evade the attacks. Yet the little girl didn't stop. She kept attacking and attacking, scattering the particles to the air; making the air hard to breathe, not only because of the fog lingering but the dust that will now hinder the respiration and sight if they're not careful. After the third times of cartwheel attack, along with wide swing from her tightened hands, Nezuko finally managed to get up and blocked the onslaught albeit with difficulties.

"W-why are you doing this?" she grunted, looking at her attacker behind her messy bangs. The girl dropped her leg and use the other to repeat the previous tactic. Nezuko still couldn't manage to dodge because of how quick her movement was. However, she was faster to get up this time and not staring like a useless victim, deflecting another kick to the side, "why are you suddenly attacking me like this? What did I do to you?!"

"Hmm? You did nothing to me," the fox girl leaped back. She put her index finger to the smiling mouth of the mask, giving an aura of a fake confusion, "but see. That's the main problem."

"You didn't do anything."

And the multitudes of attacks are now back, vicious than ever. Left, right, upward, downward. Back to the left, right twice, a distraction and upward. She couldn't keep up, her orbs going cross-eyed. At one last pitiful attempt, Nezuko let out a yell and strike her sword down—

The fox girl flipped backward—

WHAAAMM

—and landed a brutal kick under her chin, sending her flying to the sky for a few seconds before the body slammed into the earth; bruised and unconscious.

The forest went silent.

"You're having too much fun," another voice resounded from behind, making the fox girl turned. A shadow was peeking behind the tree, staring at the down Nezuko with one eyebrow rose, "you didn't even tell her what she did wrong these past few months."

"Ehehe, sorry," she lightly smacked her head as she tilted her head. And, even if they couldn't see it, the shadowy figure was sure the girl was sticking her tongue out sheepishly right about now, "it's been a while since Urokodaki-san took a woman as his apprentice so I was a bit...giddy~"

The second figure let out a long, suffering sigh, "fine. Just...leave the rest to me..."

SLAP SLAP

"Urghh..." Nezuko groaned, she rolled over to the side, hair covering half of her face, "five more minutes, niichan..."

SLAP

"Oi," a rough voice echoed, the hand that was hitting her cheek since seconds ago was increasing its strength in annoyance, "Wake up already."

Wait a minute...a rough voice? Her brother doesn't have this type of rough voice...

A stranger?!

Her eyes immediately opened, fingers clasped in her weapon that, fortunately, still within her grasp. She swung wide, didn't intend to hurt but to send them careening away from her so she could get her bearing back. The person indeed leaped back, though not without a light chuckle.

"Well, at least your situational awareness is not that rusty."

Nezuko instantly stood up, weapon to the fore. It was another person, this one is a boy. He has a peach, messy hair that also reached his shoulder. On his white complexion, his black orbs are blank and the wide scar near the right side of his mouth looked painful to have. He was wearing the same fox mask just like the fox girl did, perched at the left side of his head; Nezuko noted the mask also decorated by the same scar he had. Could it be this boy and that girl knew each other? Maybe siblings?

There's this nagging feeling behind her mind when she saw the kimono he was wearing—it's green and yellow in color, criss-cross in a complex pattern—under the dark green haori. Like she saw the same clothing somewhere before...

She couldn't quite pinpoint it though.

"Who are you? Are you that fox girl companion?" he doesn't have a color on him either. What's wrong here? Is my ability weakening somehow? "are you here to attack me too?"

"That was the plan. But she decided to jump in and I'm stuck as a babysitter," he scoffed. It doesn't have that irritated tone within it, however. His words may be harsh yet it was clear he said those in a jest, "don't lose that stance. Because now, you're going to train with me."

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The boy told her that his name is Sabito. And the fox girl is Makomo.

In the morning, they went through the basics training. Sabito pointed out the defect in her style, correcting her unnecessary movement and bad habits. At noon, he'll test that progress by beating the crap out of her—err, by doing a sword training. But really, Sabito was so strong that Nezuko basically spent the rest of her time rolling around on the ground and being whacked right and left like a sack of sandbag; honestly, he was just as strict and ruthless as Sakonji. Then in the evening, she'll continue by fighting Makomo, battered up and exhausted she was, they didn't care. As long as she finished the training schedule they provided for her. The long-haired girl was still questioning why these two strangers did this for her, training her. Where did he come from?

So she asked Sabito one day—when she was swinging her blade and he was watching from on top of the boulder. The girl thought he'll not answer, he was silent for too long. Until his mouth parted and he told her a very short explanation.

We're just trying to repay our debt to Urokodaki-san.

They aren't sibling, both of them are orphans. The old man in a tengu mask took them in and raised them; that what he meant by 'repaying their debt'. Sabito said there are other children too, watching her around the shadow of the trees and assessing her improvement. Nezuko's body was a bit tense after knowing that fact. Kind of embarrassed because then, they've known about every single mistake she did and she felt like it doesn't show much confidence in her skills to the other Sakonji's pride apprentices. The peach-haired boy ushered that notion away by swinging the bokken on her head hard enough, she was still reeling with a headache that night.

Speaking about Sakonji, he knew something happened at the day Sabito and Makomo appeared. Because Nezuko was sporting a lot more injuries than she should when she trained alone. She didn't tell him anything though, no matter how probing his stare was. And asked her brother not to said anything either—not that he could. But the old man is master in reading other people's gesture so she was sure he could picture the whole ordeal somehow—a bit of petty revenge for not giving her any clue of what should she do next, even though Nezuko knew they need to tackle the problem by their lonesome sometimes. That's how you grew up, by thinking of the solution with your own head.

"Total concentration breathing accelerates your blood flow and heartbeat. And your temperature shoots up. You're still human, but you get strong like a demon," he said, "you expand your lungs and bring lots of air into your blood. Your blood will boil, your bones will strengthen, your muscles will expand. You'll feel like you're burning up but you'll get strong."

"Burning up? Even though we're practicing Breath of Water Style?"

"The element is not the issue. You can learn Wind Style for all I know and your body will still feel the heat," Sabito shook his head, "it's not the element, it's your body. Your body is overwhelmed by the sudden influx of energy, hence the burning up."

"I see..." she...kind of understand. Maybe, "so what should I do to get to that stage?"

It was small, but she could see the smirk hidden within that unmoving face, Nezuko unconsciously shivered. He unsheathed his bokken from his waist, legs stretched to the back, "train hard until you feel like you're gonna die. That, is the only thing you can do," and he lept.

Nezuka wanna cry.

It took a lot of beating, a lot of bandaging the wounds and a lot of fussing from her precious brother before they changed their training weapon to the real weapon—Sabito changed his bokken into a sharp katana. And Makomo wore two small yet dangerous daggers tied into her feet—then their training regime increased; like it wasn't difficult enough already, it's almost beyond hell now. Another six months had passed—making it two years that they are now officially a freeloader in Sakonji's residence—and, maybe just pure luck or the training had been successful, Nezuko's sword land a hit at a particular angle, Sabito's own weapon was thrown away, slipping from his startled grip. It was tense for a few seconds, the trainer's orbs blinking in befuddlement and the trainee was surprised beyond measure; thinking it was only a dream and was on the verge of slapping herself awake. Before the boy let a low cackle and turned to her, hands on his hips.

"You've finally done it."

The next day, Makomo was there, the tip of the deadly shoes was now looked a bit purple—don't tell her it laced with poison today?—The contest was simple. The stronger, faster blade wins.

One moment of silence. And they moved.

The fight was over in an instant. That day, at that moment, for the first time, Nezuko's blade reached Makomo first.

Her mask cracked in two, falling to the ground with a loud clatter, she gasped. Makomo is a pretty girl. Blank, blue orbs and small lips. When Nezuko won, the fox girl smiled, eyes closed. It looks refreshing yet at the same time, sad. It made the long-haired girl's stomach tightened in a knot. She didn't know why.

"I knew I won't stand a chance the moment you beat Sabito-kun." She said.

"H-huh?"

"You don't know?" Makomo giggled, "Sabito is the strongest swordsman in our circle. The moment you beat him is the moment you beat all of us~"

Nezuko was pretty sure her jaw had dropped to the ground at that revelation.

No wonder he was so powerful! And his strikes hit like a lead itself!

"Win, Nezuko-chan," fog started integrating towards her, covering half of her face. Only leaving the mouth visible as she continued, "...against them too," before she completely disappeared.

And Nezuko found that her sword hadn't cut Makomo's mask. But had split the humongous boulder instead.

She finally passed her final test.

(A/N): I don't know...I just want to change her opponent. Instead of Sabito, Nezuko got Makomo `3`

The manga and anime don't really tell us what Makomo's weapon is. I'm sure it's just a normal sword like any other. But when they said 'she's fragile but her movement is fast', the first thing that came to my mind was 'oh so she's just like Sanji from One Piece'. I don't know how that conclusion came, but it was interesting so I decided to use that idea here :'D

The dagger is coated with strong paralyzing poison. Didn't know if it will work on the Upper-Level Demon, but it worked wonderfully to a normal demon. Or at least, if it doesn't really work, the paralyzed effect will stay for a second for other demon-slayer to finish the job. She's weak so Sakonji trained her more to be a support role rather than the main forces. Of course, the dagger is long enough to behead the demon's head but her main role is to support. Maybe if she's still alive, she can learn other methods of poison from Shinobu; she's one of the Pillars who uses poison to kill the demon.

Also, I re-read the manga and saw Shinobu actually has a hidden knife in her sandals. Even tho it's only a normal weapon and not the Demon Slayer blade. So, me changing Makomo's weapon into hidden daggers is actually not that much of an incredulous idea lol.

I seriously don't remember about this fact tho'. Good thing I re-read the manga :'D