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 15

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With Tanjiro tasked to drag the growling demon away while the lime-haired student brings the injured wife inside—she was unconscious now. Nezuko hoped it was only because of shock and not blood loss—they arrived at two-stories house that was located behind the dead end of an alleyway—they literally walked through a wall like it was nothing just to reach this place—far away from even the outskirt of town. Nezuko stopped for a second when she saw something, nailed at the roof of the front porch; a white paper with a strange symbol on it. The symbol itself looked like an eye, with two curved lines at either side and a series of leaf-like line at every four corners, "it was a cloaking spell," the student explained when he saw her staring, "I cast it so it'll mask this house presence from other people's sight."

She hummed in understanding. That was why when they passed through the wall, Nezuko could not see their color anymore. The demon hunter stepped inside, standing to the side as to not be a bother when the boy put the wife to the bed. He then ordered Tanjiro to follow him to the dungeon, they have to hold the husband in the jail for now so he will stop trying to attack anyone in sight. When they were gone, the ponytail girl stepped closer. The wife's face was still pale, grunting and moving around a bit restlessly, likely having a nightmare.

"Do you think she'll be okay?" Nezuko asked, watching the lady clean the wound.

"Yes. Thanks to your brother, the wound is not that deep," she said, finishing the treatment with a flourish. She cradled her hair, trying to chase away the bad dream.

"Umm..." the second siblings wrung her fingers, "does it...fell uncomfortable for you to handle the wound of a human?"

"Obviously not!" then tensed when the voice of the student boomed in the silent clinic, a sarcastic undertone was clear from the sharp answer. They were back, with the lime-haired teen looking suspiciously at the happy Tanjiro, who bounded to Nezuko and started aiming for the bag on her back. She turned away from the reaching hand, however, "as demons, we must endure the saliva brought on by the smell of flesh and blood. That's what you think, right? Just a mindless beast in which we'll just pounce at any prey we found? Well, you thought wrong, stupid girl..."

"Wha—"

"Don't be so rude," the demon doctor interjected, "I haven't introduced myself yet. My name is Tamayo and this child is Yushiro. Please do excuse him. He's a bit rough around the edge but he's a nice kid."

"Well..." Nezuko took a glance at Yushiro, who was glaring at the floor with such intensity that, if a stare can kill people, he'll surely have become a mass murderer right about now. She turned again when Tanjiro was still chasing after the wooden box, "I can't really do anything to someone who hates my guts even though I didn't say anything rude though..."

"And to answer your question, it does not feel particularly uncomfortable. I have an easier time with it compared to normal demons," Tamayo put a hand on her chest and gave a small smile, "I am able to manipulate my body to my own wish. Which made it possible for me to remove Kibutsuji's curse as well."

Curse?

"I can survive even without partaking human flesh. All I need is to drink a small amount of blood," she chuckled when she saw Nezuko turned a bit wary at that. Still evading her brother's advance, by the way, "no, we don't hunt humans like normal demons. We get our food from buying the blood that was originally given for transfusions from people who don't have a lot of money."

Ah, so that's why. It's been nagging at the back of her back, something about them seem different. Now she knew. Their fog is black like the usual demon. But somehow, it doesn't fell...disgusting, nasty. They were still a lot more demon than human, though. Because there is no other color in their fog, not like Tanjiro, who still retained the burgundy in it even if it was so little, she had to really squinted to look at it.

"Yushiro is even more impressive. As he only needs a minuscule amount of blood to survive," Nezuko accepted the tea made by the said boy, though with a bit too much force he almost spilled it on her haori. The ponytail girl took the bag off of her back and put it in front of her, away from her brother wandering hands, Tanjiro pouted, "I was the one who transformed him into a demon."

"W-What?"

"What what?!" Yushiro growled, seems like he took offense at the incredulous tone the pink haori wearer unconsciously utter, "don't you judge Tamayo-sama! She's my savior, I'm not gonna let you look down at her because of a misunderstanding!"

"Wait, that was not my intention! I was wondering how—"

"How can I, a normal demon, turned another human into a demon as well, was it?" Tamayo ensured, in which Nezuko nodded, "indeed, people other than Kibutsuji are unable to increase the number of demons, this is factually correct. However," she took another sip and stared at the standing leaf on the surface, "after going through over 200 years, the only person that was able to transform into a demon was Yushiro."

"I won't increase the number of our kind, of course," the black eyes stared at her, trying to make her intention honest and clear using the stare alone, "but to a person that is plagued by disease without a cure and is about to die, this is the only option I can offer to them."

"Tamayo-sama asked me if I want to continue living as a demon before she granted me her blood," the student tsked, "it was my choice. Don't you dare hate her for it."

"No, no. I was just so...astonish by it. It was really Incredible..." she gasped, full of awe and pure admiration. These two were so incredible. To think these nice demons exist. Before she closed her eyes, put the tea on the floor, and pull the box away while glaring at the sheepish Tanjiro; who was laying stomach-down beneath her face, "niichan, I told you not to eat any more snacks!"

Tanjiro whined.

"No, you already eat dinner. Two bowls of noodle, I may add. There's no way you're still hungry!"

He clasped his hands and widened his eyes, giving her a look of a kicked puppy.

"I said no."

Along with small tears at the corner of it.

"Niichan..."

That orbs glimmered with innocence.

"Uurghh...FINE!" she slammed the box back down and shoved it to her brother, Tanjiro immediately cheered. Nezuko stopped him by the head when he lunged onto it eagerly, however, and warned, "just one snack. I'm not giving you more or I'm going to let you starve for a day."

(She will not, as he replenish his energy that way and she could not let him weaken in a time of need when their job is a lot more dangerous from now on than just being a child of coal burner. But her brother won't stop if she doesn't threaten him from the start so that's that)

The ginger-haired boy nodded frantically. He picked up another anpan from the compartment and, after pulling out the scarf that still somehow stay on his head even after the tumbling and the green bamboo from its place, he ate the bread; a lot more slowly now to treasure the flavor as this was his last snack of the day. The pleasant atmosphere was immediately gone, now changed into something akin to shock. Nezuko could guess why.

"What the heck?" Yushiro mumbled.

"Is...your brother eating human food?" Tamayo incredulously asked, hands on her mouth to cover her bafflement.

"Yes, my mentor said that his human side is a lot more prominent than the other," she answered, cradling her finger at his ginger hair. The younger sister swore Tanjiro purred under the pat, "so instead of eating human flesh or uh...in your case, drinking some blood, he eats food to survive. And sometimes sleeping too."

"Do you know the reason why?" the doctor scooted closer, watching every move her brother made with intense scrutiny, her eyes almost glowing. Like a kid getting their dream present at their birthday after waiting for years. The student, after his confusion at the bizarre scenery was gone, schooled his expression and sent a glare at the happily-eating beast (Aaah...now she understand. Nezuko is one-hundred percent sure Yushiro hate everyone on the sole basis that they took the attention of Tamayo away from him. Just jealousy of an adolescent in love. Something she understands via fairy-tale books her mother loved to read for her when she was still a child, yet hasn't experienced it first hand as she was too busy with a more serious problem at hand. That means Nezuko was not at fault for the unclear resentment the boy harbored towards her, she sighed in relief). Tamayo tilted her head when he saw Tanjiro also drank the tea his sister abandoned, mumbling, "maybe I can finally make a medicine that will turn the demon back into a human now."

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It took several seconds for her to digest that exact word the pretty lady uttered. And when she realized the implication, she almost stood up in surprise, "you...you can turn a demon back into a human?"

"You have the cure?!" Nezuko leaned over in record time, clasping her clammy palm on her shoulder. Burgundy orbs desperate and voice almost begging, "p-please! Can I have one—"

"Calm down, Nezuko-san," Tamayo cut her plea, gently lifted her hand from her figure. Yushiro was growling in the background, his gesture was clear that he intended to tackle the demon hunter away from his precious person. Yet couldn't because Tanjiro was holding him back by the arm with one hand, still munching on the food, sinking the nail in his delicate skin; not that deep to draw blood but deep enough to make his warning clear. The two women ignored the little squabble from their male companions—those two were now looking at each other. Or glaring heatedly in the case of the student and staring innocently in the case of the oldest Kamado's sibling—then continue to converse, "It's been my wish to create this medication the moment I know not all beasts are bad. Some were turned against their will. And some could only walk this depressing path because there's no other way. If I can make the remedy, it'll give the victims back their previous life, maybe cure their illness as the demon blood already washed the disease away, and Kibutsuji cannot further his army of man-eating devils."

"Then—"

"Unfortunately," she again interjected, "at my current stage, I cannot turn a demon back into a human."

"Wha—"

"However, no matter what kind of sickness it is, there will always be methods and medicines for it," she gave her a reassuring smile, a view that calmed Nezuko's drumming heart, "I will do my best to research and develop a method of treatment."

"You can count on me for this"

Still in Asakusa, at the same time, at a different place, were two shadowy figures moving, stalking the empty street. A teenager with short black hair was crawling on the ground. The big, blue marbles on his neck jingled as he moved, his green-black yukata was pulled a bit from the ground as he didn't want to get it dirty. He raised his hands and at the both of his palms exists an eye, with a green sclera and red eyes, a black arrow as it pupil. The eyes somehow sniffed, catching up the scent that was already long gone.

"Can you see it?" another one asked. It was a girl a bit younger than the previous, with black hair and red highlight at the bottom. She was bouncing the colorful kemari ball, making her black obi that covered the orange kimono swayed, following the gravity. Ring, ring, ring, the ball sounded, it created a beautiful yet ominous sound in this dark night without stars.

"Of course. I see footprints," the boy snickered, crazed manic undertone seeped from his voice. His real eyes were still closed as he preferred to use the one on his palms to see, staring at the said footprints—who actually looked like red arrows covered by white, otherworldly fire—appearing on the ground one after another, pointing him to the place he wanted, "the boy wearing a uniform turned around there and circled a long way around. And then there were three other people and one of them is wearing a huge box. Look like that one is our target"

"How do we kill them, ufufufu?" the girl giggled like a happy child. Even if those yellow eyes with horizontal pupil were clearly radiating madness, "I feel this power coursing through me. Because we received the blood from the great one just now~"

"Well, it was obvious right?" the innocent quirk of lips of the boy turned sharped, pointed fangs peeked beneath the demented smirk.

"We are going to slaughter her as cruelly as possible"

Tamayo explained a step by step she believed will help her in creating the treatment. First, she wanted to investigate Tanjiro's blood. Nezuko's mentor theorized the reason why her sibling was more human than a demon was because he is an older brother, a protective older brother at that that, even when he lost his memory, his instinct to protect the youngest was there so he knew not to attack Nezuko. Then they had taught him not to attack innocent civilians too. Just because those people are not his siblings or family, doesn't mean he should abandon them. Sakonji said he practically like a toddler since he was turned into a beast, mimicking everything he saw. Yushiro scoffed at that half-baked theory—too full of optimism and sentiment—yet he didn't outright deny it. Saying that, sibling-theory aside, the amount of blood Tanjiro received or, maybe, the blood-relation itself play a part in it. In which Tamayo agreed.

(Honestly, Nezuko thought the reason why Yushiro didn't want to debunk Sakonji's theory right away because it almost sounded like a fate. 'It was a fate that family will always love each other'. 'It was fate when people fall in love then live happily ever after'. And with his intoxication towards the pretty lady, he wanted to believe that fate of love really does exist. She won't say anything, though. Didn't want to anger him any longer)

(It was still endearing as heck, she almost smile)

Second, she wanted her to gather blood from demons with Kibutsuji blood coursing through their veins as much as possible. The doctor surmised that Tanjiro was currently at a very rare and very precarious stage of development, she explained while observing the ginger-haired boy who was now playing with Nezuko's hair and making new sets of braid from it (it was still a bit messy but it was a great improvement from before).

That was also the reason why in their previous battle, her brother went a bit...deranged.

The human side was buried for a while when his emotion was in a jumble. And the demon side sleeping within it took over, making him a lot stronger yet a lot crueler. That was easily explained by the changed of eyes color. Demons sometimes undergo drastic transformations when they were turned into the said devil; a good example was the green demon from the Final Selection mountain ground. He had a human appearance before he turned into that disgusting form. Tamayo didn't know if this was a fact or just a mere rumor, but if you have dark coloration when you were still a human, if you do undergo changes, the color will turn lighter when you're a demon and possibly, the other way around too; Yushiro is a good example of that, as his hair was full black when he was a human yet now turned half-lime. In Tanjiro's case, the lighter his color was, the more he loses his memory and his humanity along with it.

Because the beast who turned him into a demon was not the nice Tamayo but the evil Muzan.

The ginger color is dull, dull, dull and Nezuko hated it. However, if this information is indeed correct, then the theory of him retaining more of his human side than the devil one was now confirmed. Because ginger is a lot closer to red than yellow. And her sibling's previous color is burgundy. Meaning, if you put it into numbers, his scale of transformation was under five instead of over it. Meaning, that Tanjiro might become the key to unlocking the mystery of man-eating demon in the future.

"This second thing I want from you is a very cruel one," Tamayo lamented, head bowed, "the demon with thick Kibutsuji's blood coursing in them are demons that have...gained a massive amount of strength from Kibutsuji himself. It won't be an easy task, robbing these demons of their blood. Even so—"

"—are you willing to accept my request?"

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"You don't have to ask for my confirmation on this, Tamayo-san. Of course, I will," she promptly answered without any hesitation. Her hand reached back and managed to cradle the demon brother's cheek, "if you managed to create and manufacture the medicine, not only niichan, the lives of even more people—be it humans or demons—will be saved right?" she gave her a grin, "this may sound like I'm copying you but I've been wanting to turn other demons back to human too, the moment I promised myself to cure niichan. Demons were humans, they have their own emotion. Am I right?"

Tamayo blinked at the firm declaration, blinded by the sincerity in it. Then she smiled, "yes. You're right. Thank you, Nezuko-san." Tiny and faint, yet so beautiful Nezuko actually blushed!

...Yushiro expression was outright murderous, Nezuko actually sweat.

It was an instant reaction. Tanjiro's nose twitched. Then Yushiro's eyes widened.

(Someone had torn the cloaking spell down!)

Tanjiro wrapped his hands around her. While Yushiro went to grabbed Tamayo and shouted.

"GET DOWN!"

BAM BAM BAM BAM BAM

Before something crashed through the building, bouncing on the wall, floor, and ceiling. Crushing every single place whatever-it-was touched.

A kemari ball rolled to a stop, making a nice, short jingle.

RING

(A/N): So...about the color. This is just a theory of mine that I pulled out of my ass after looking at the evidence. I don't know if the theory of 'lighter = darker' is correct. There's one demon that actually has dark hair when she's a demon but light hair when she was a human. One of the Upper Demon Moon, Daki the hostess, first appeared at chapter 73. However, the moment she turned into 'full-blown' demon, her hair immediately turned light, even before canon!Tanjiro talk-no-jutsued her. So I don't know if her hair really changed into a darker one when she's a demon or she was just slightly changing her appearance to blend into the human crowd and disguised herself as a hostess.

But 'darker = lighter' seems to be a pattern as of now. There are two demons, other than Yushiro, that have a darker hair when they were human but turned lighter when they changed into a demon; one of the Lower Demon Moon, Rui the Spider demon, first appeared at chapter 29. And one of the Upper Demon Moon, Akaza the one with tattoo all over his body, first appeared at chapter 63.

So, before the latest installation of the next chapter finally confirm or debunk this, I'm going to make this theory canon `3`