A/N: Thank you very much for the enthusiastic response last chapter. I was not expecting it! To be honest, I was worried that the readers won't take the whole "Tanjirou conquering the sun early" thing very well. I'm glad you all liked it! Let's see how that big detail will change things moving forward, shall we? ;)

Chapter Ten: Ubuyashiki Kagaya

The sound of footsteps roused Tanjirou from his silent daydreaming. Standing outside near the front of Urokodaki's hut where he was diligently laying the washed bedsheets on the clothesline so they would dry under the sun, Tanjirou stared at the three figures that were closing in on him from a distance. There was a man and a woman, and a young child that Tanjirou would guess must be their daughter, given the resemblance she had to the two adults. She had the man's black hair, and the woman's piercing eyes. They moved slow but graceful, laden with a certain sense of dignity, as if they were royalty and not just mere travelers walking along a dirt path. The woman was carrying something in a box strapped to her back, as well as an umbrella to keep the harsh sun from beating down on the three of them. The man seemed frail, his hand supported by his daughter. Some kind of curse scar was covering half of his face, but he retained a gentle aura about him, a certain tranquility.

The wind shifted, and Tanjirou caught a whiff of their scents. It made his nose wrinkle. The smell of wisteria clung to them like second skin, but there was something to it too— the smell of sickness, of underlying tragedy. It clung especially well to the frail man, and Tanjirou wondered if it had something to do with that sickly scar. Tanjirou tilted his head curiously at them, unsure what to think. He let them walk closer until the man was right in front of him, smiling serenely. Up close, Tanjirou could see that one of his eyes were blank and unfocused. He was half-blind. That one remaining working eye seemed to take Tanjirou all in, studying his features, pausing for a moment at something on his forehead, before meeting his gaze again.

"Ah, you must be Tanjirou," the man stated nonchalantly. Tanjirou's eyes widened in surprise. His voice was soft and calm, and it made the demon's head feel light and fluffy. He didn't know who this person was. He wondered how he knew his name.

"Tanjirou, are you done with the bedsheets—" he heard Urokodaki ask behind him, but then their mentor made a strangled sound. Tanjirou turned his head to look just in time to see Urokodaki freeze in his tracks, the firewood he was holding falling down to the ground. As soon as the man turned his head to smile at the old man, Urokodaki fell to his knees on the ground in deference. Tanjirou's eyes widened once again. He had never seen Urokodaki show this level of respect to someone before.

"Oyakata-sama, I am blessed to be in your presence," Urokodaki said stiffly. "What brings you here, so far from the headquarters..."

"Rise, my child," the man replied, even though he looked evidently younger than the old Urokodaki. "I am merely here for a visit, as well as a delivery. I was curious about the contents of your letter. I found it prudent to meet the very first sun-resistant demon myself."

To meet me? Tanjirou frowned. Someone of power, someone evidently up in the ranks of (Tanjirou assumed) the Demon Slayer Corps, was showing interest in him. He knew he was different. He knew he was an anomaly, not only because he refused to eat humans, but because he can now walk under the sun as well. What did this person want from him? He should probably get worried, but the man's scent showed no malice, no ill intent. His smile was sincere. Tanjirou found himself relaxing in his presence.

"Pardon the intrusion, but this conversation would better be done inside the house, with all three of you, over a cup of tea," the man said. "Would you call in Kamado Nezuko for me?"

The six of them sat around the irori, a small flame lit on the hearth to heat up water for their tea. The man and his family sat on one side, all straightened backs and quiet grace, and Tanjirou found himself shifting nervously as he subconsciously leaned toward Nezuko, who met the newcomer's gazes fearlessly, sure of herself. Urokodaki was silent as he poured the tea into cups, offering them to everyone one by one. Even Tanjirou got one, though all he could do was stare at the liquid silently. At least the warmth of the cup was settling his nerves a little bit. The man accepted his cup with a graceful nod, before staring back at the Kamado siblings. When he spoke, his voice held the same calm and soothing tone.

"Let us get the pleasantries out of the way. My name is Ubuyashiki Kagaya. I am the current head of the Ubuyashiki household, as well as the 97th leader of the Demon Slayer Corps. This is my wife, Amane, and my son, Kiriya. It is a pleasure to meet you."

Son? Tanjirou flushed a little bit, embarrassed that the whole time, he had thought the child was his daughter. He couldn't be blamed for the mistake though, as Kiriya was wearing what most would consider feminine attire— a purple flower-print kimono and a hairpin resembling wisteria flowers. He also looked quite feminine in his own right, his features smooth and delicate, evidently not having gone through puberty yet. Tanjirou wondered how old he is. He still looked very young.

Nezuko seemed surprised with the revelation as well, but she did well to hide it. She nodded at her superior, tone respectful but guarded. "My name is Kamado Nezuko. This is my older brother, Kamado Tanjirou. Pleased to meet you too, Oyakata-sama."

Kagaya smiled. "Kamado Nezuko. Sakonji told me that you have just passed the Final Selection. You must have worked hard. Congratulations."

At that, Nezuko looked a little taken off guard, startled by the compliment. "T-Thank you."

Silence. Nothing was heard aside from Kagaya quietly sipping his tea. Even though he wasn't looking at Tanjirou, the demon felt as if his attention was still directed at him. Tanjirou fiddled his thumbs around his cup a little bit, nervous to be under such scrutiny. It didn't seem like bad scrutiny though. It didn't feel like either him or Nezuko was in danger. It was just a gentle curiosity that Kagaya exuded from his scent. There was also an undertone of interest, of intrigue. Tanjirou supposed it can't be helped.

"I found out your story through Sakonji's letter," Kagaya continued. "I am sorry for your loss—"

"Shall we get to the point, Oyakata-sama?" Nezuko interrupted, her voice hard. "I've heard you came all the way here because of my brother."

Kagaya did not look fazed. He looked thoughtful. "Of course… if you wish so. Kamado Tanjirou's case is… well, it would not be an exaggeration to say we have not seen a case like this in a thousand years. Ever since the rise of the demons from the first demon progenitor, Kibutsuji Muzan, there has been no demon who had developed a resistance to the sun. If there was, they would have been devoured by Muzan already, as it is one of his main goals: to achieve absolute perfection, to be unkillable."

Nezuko tensed.

"Suffice to say, that Kibutsuji would no doubt go after your brother, if he finds out. The fact that he hasn't yet must mean that Tanjirou had already somehow burned away Muzan's control over him. That's something good, at least. But I believe he would come after both of you, either way. If your family truly has a connection to the Sun Breathing Form, Muzan will try his best to kill you, anyway." Kagaya stared down at the cup in his hands, contemplative. "I wish I am bringing better news. Forgive me."

Tanjirou and Nezuko glanced at each other, and Tanjirou's hand itched to close around his little sister's. It wasn't like this was news. Since the day they found out that they had a demon slayer heritage, Urokodaki had proposed this as a possibility. Personally, Tanjirou did not mind Muzan going after him. It would make it easier to find the monster that massacred their family. He worried about Nezuko though, and what being around him would mean for her safety. He wondered if he would even stand a chance against the most powerful demon there is. If he was good enough, strong enough.

He remembered his promise that day the monster ruined their lives. I'll hunt you down and end you even from beyond the grave. It was a promise he still kept close to his heart. He couldn't bear the idea of Kibutsuji Muzan still being out there, Tanjirou's family unavenged, killing people and destroying families— he couldn't stand it. Nezuko's goal may be to find a cure for him, but Tanjirou's goal was to end this nightmare from the source. Demons weren't inherently evil, he knew— but Kibutsuji Muzan. That man was malice itself.

"It doesn't matter if he would be after us or not," Nezuko answered for the two of them. "The only thing I care about is finding a cure for my brother. If Kibutsuji Muzan becomes a hindrance to that goal, I will cut him down with my blade."

Not before I cut him with mine, Tanjirou thought vindictively.

"As I'm sure you would," Kagaya replied with a pleasant smile, as if they were talking about the weather. "I am aware that you siblings have a personal vendetta, but I assure you the Demon Slayer Corps is just as determined to get rid of Kibutsuji Muzan as you are. There are people who have trained for years, willing to put their lives on the line, so that the threat he poses may be stopped once and for all. For starters, there are the Pillars, talented swordsmen they all are, and I am sure they are just as determined to face him. Unfortunately, there have been very few chances to do so. He is a master at hiding himself. We have not seen hide nor hair of him in literal centuries. Tanjirou's existence, as well your own Nezuko, may be the missing key we all need to rouse him out of hiding. And for that, I came here with a selfish request."

"A request?" Nezuko pressed.

Kagaya nodded. "If it was up to me, I would suggest we hide Tanjirou away from the world for the time being. If Kibutsuji Muzan managed to devour him and acquire his sun-resistance, it would be a detriment to the entire humankind. It would be better for him, safer for him—"

Tanjirou rose to his feet indignantly, spilling his tea all over the wooden floor. He was not going to stay hidden away in secret while Kibutsuji Muzan goes after Nezuko anyway! He shook his head to side to side vehemently, letting out loud growls to express his displeasure. He's going to stay with Nezuko. He will protect her and stay by her side! That's what he promised to his mother's memory! He promised he would take care of Nezuko… no matter what it took.

Kagaya seemed to anticipate his reaction. "—but I assumed this idea would be met with resistance." Tanjirou glared at him, and he let out a quiet chuckle, one that seemed to tinkle in the tensed silence of the room. "Please sit back down, Tanjirou. I have no intention of forcing you or Nezuko into anything. I may be Nezuko's superior, but your lives remain your own."

Tanjirou let out some more low growls, unconvinced.

"My brother and I already talked about what we think we should do from now on," Nezuko interjected, and it was true. Well, 'talked' was a generous term as Tanjirou was merely able to let out grunts and growls, but they discussed it all the same. Especially after the development of Tanjirou's sun resistance. "We thought that it would be better not to tell anyone we encounter the truth about what he is. That he should pretend to be a human— and it shouldn't be that hard. Nobody would think a demon could walk in the sun anyway, and Onii-chan already looked human enough in his natural state. Nobody should be able to tell… right?" the uncertainty creeped on her tone at the last sentence, glancing back at Tanjirou.

Kagaya hummed. "Perhaps. Though the stronger a demon gets, the more easily they could tell other demons apart by their presence alone. Kibutsuji Muzan is no exception. There is also the fact that he may very well recognize your brother, as he was the one who turned him that day. Kibutsuji Muzan has an uncanny ability to see through other demon's heads as well, sometimes even remotely, and while Tanjirou here has no doubt already severed his connection to Kibutsuji already, he may get information from other demons you encounter, other demons you slay on the way. Not to mention the word of mouth that may spread if the humans and other demon slayers around you find out. A sun-resistant demon is a very big deal. There's no way people won't talk about it."

Nezuko looked worried, and Tanjirou wondered if she was considering giving him up to be kept under protection after all. He would fight tooth and nail, fang and claw— to make sure that doesn't happen. Nezuko didn't get to tell him what to do. He was still Nezuko's older brother, after all— even though Nezuko was now physically older than him.

"There is, however, one way we could conceivably hide Tanjirou's nature from everyone without locking him up somewhere, and it relates to the request I mentioned earlier," Kagaya paused as if bracing himself. "According to our records, Tanjirou is not the only demon who is not in league with Kibutsuji Muzan. There is another. She goes by the name Tamayo, and to this day, she remains hidden even from Kibutsuji himself— an incredible feat. I believe with her methods, she may be able to help us hide Tanjirou's secret long enough, until the time is right. If we are lucky, she may even be able to assist the Corps in figuring out a proper plan of attack. As much as it pains me to admit, the Demon Slayer Corps is not ready for an all-out war with Kibutsuji Muzan. Not at this time. But when we finally are, as I hope we will be in my lifetime, I would like to ask if you and especially Tanjirou would be willing to draw him out, to act as bait, as Tanjirou will no doubt be an effective one. Tanjirou, could you do that?"

Tanjirou did not even have to think about it. He immediately nodded, clenching his fists in determination. Anything to bring down that monster. Anything to free this world of his evil.

"This Tamayo-person... Do you think she will really help us? Where can we find her?" Nezuko asked.

"We are fortunate enough to have information of where she is at this time. My sources say she's somewhere in Asakusa, although exactly where in that city we are not very certain. If she did not want to be found, she would not be found. There is the fact that she is very wary of demon slayers as well, and would not approach us on her own, despite our shared goals. I was hoping that meeting someone who toes the line between demons and demon slayers, someone like the two of you whose unique circumstances give you the chance to bridge both sides, would encourage her to hear us out." Kagaya smiled, before his tone turned commanding. "That is why, for your first mission, I'd like you to go to Asakusa and find Tamayo-san, and tell her of the Demon Slayer Corps's intentions to join forces. Could you do that for me, Kamado Nezuko?"

Nezuko's back straightened up. "Y-Yes, Oyakata-sama."

Kagaya's smile turned fond. "You are a good child." He turned his head slightly towards his companions, his wife in particular. "Amane-san, the packages."

"Yes," Amane said as she took the box that was tied to her back earlier and placed it on top of her lap, unwrapping the cloth around it carefully. The fight in him gone, Tanjirou found himself settling back on the floor as he watched in curiosity. The box was small in width but very long, and Tanjirou soon understood why: inside there were two katanas encased in their sheathes, and Tanjirou did not need anyone to tell him they were nichirin. This must be what Kagaya meant earlier when he said he was here for a delivery. Nezuko's blade has finally arrived.

"Kamado Nezuko's nichirin sword," Amane said tonelessly as she held the katana in front of her like it was something sacred, handing the blade to Kagaya, who then handed it to Nezuko. Nezuko looked a little overwhelmed, surely not expecting that the leader of the Corps himself would be the one handing her her very own blade, but she looked happy nonetheless. She held the handle, admiring it.

"Scarlet Crimson Sand and Scarlet Crimson Ore, obtained from the mountain closest to the sun. The process produces steel that can absorb sunlight. This blade is made by Haganezuka Hotaru, I believe, one of our very best. I hope it will be useful in your journey." Kagaya said.

"Thank you very much," Nezuko murmured.

"Go on, draw it," Urokodaki spoke for the first time since this talk started. Tanjirou had nearly forgotten he was there. "Nichirin swords are also called Color-Changing Swords. They change color depending on the bearer."

Nezuko hesitated, but eventually she drew the blade, holding it in both hands. Tanjirou watched in fascination as the color indeed slowly changed, starting from the hilt end to the tip, though not in the way either of the siblings expected. Instead of a single, solid color, there were two— a blue hue reminiscent of Urokodaki and Giyuu's blades, but in the middle there was a black band that if Tanjirou stared intently, looked like it resembled the shape of vines and leaves. Nezuko blinked at the color, looking slightly troubled.

"It's not… a solid color," she whispered.

Urokodaki hummed, though Tanjirou noted there was a certain scent of pride. "Blue for water breathing, I suppose— though don't think too hard about the black bits. The reason for why the nichirin blades change color and what the color means remain mostly a mystery at this point, so it really shouldn't matter."

"Not having a solid color is not completely uncommon," Kagaya reassured her. "Some of our current pillars do not have a solid color on their blades either. Perhaps it is a sign that you will rise just as far as they have."

Nezuko flushed a little bit as she sheathed her sword. She seemed a little pleased at the idea of rising in the ranks as Kagaya suggested, and Tanjirou felt happy for her. He let out a few soft hums of encouragement, at least until Amane took out the second katana from the box, held it like the way he held Nezuko's, and intoned, "Kamado Tanjirou's nichirin sword."

Tanjirou's eyes widened as Kagaya took the sword from his wife's hands and offered it to him. Nezuko and Urokodaki also seemed genuinely astonished. Kagaya had a certain quality to his smile that suggested he was enjoying their surprise, their shell-shocked faces. Tanjirou hesitated, meeting the man's eyes— why? he wanted to say. Why are you giving me this?

"As I read from Sakonji's letter, you are a swordsman too, are you not? Kamado Tanjirou," Kagaya asked.

That's true— he was. Kind of. He had trained alongside Nezuko for two years. While she honed her mastery of Water Breathing, he trained himself in Hinokami Kagura's twelve forms. But that didn't make him a demon slayer. He had not passed any kind of Final Selection— was physically unable to, considering what Nezuko told him about it: a prison of wisteria flowers in a solitary mountain, keeping all the demons locked inside. He didn't know if he was worthy to have his own nichirin blade, didn't know if he deserved it. All this time he had not even entertained the idea of getting one, so certain he was that he wouldn't. And yet now Ubuyashiki Kagaya, the leader of the Demon Slayer Corps himself, was offering him a blade. Tanjirou did not know how to react.

He felt someone tap his back, and when he turned his head to look it was Urokodaki, urging him forward. To take the sword. Tanjirou hesitated, but he followed their mentor's guidance. The sword felt heavy and dangerous on Tanjirou's hands. Uncertain, he looked back at Kagaya, and then at Urokodaki and Nezuko as well, gauging their reactions. Kagaya looked serene as usual, Nezuko looked encouraging, and Urokodaki smelled proud. He let out a noise of confusion from the back of his throat, still unsure about all of this. Why? He desperately wanted to ask Kagaya. At some point, it seemed the looks he was giving the man finally got through, and he finally decided to explain himself.

"Your Hinokami Kagura is the Sun Breathing Form, is it not?" Kagaya asked. Tanjirou nodded. After thinking about that night over and over, recalling the things that monster had said, he was certain that that was the true name of their family's tradition. Without a doubt. Kagaya nodded back. "The Sun Breathing Form is the very first form that was created, from which all the other breathing forms were derived from. It would be truly a shame for the sole remaining sun breath user of this generation, to never own his own nichirin blade. So I decided to correct that. Call it a whim of mine, if you are so inclined. Please go ahead and draw it."

The information about Sun Breathing left Tanjirou reeling. He didn't realize it would be such a big deal. The breathing form from which all breathing forms were derived from? Passed down as the Hinokami Kagura of their humble coal-burner family? It seemed unreal. Not for the first time, Tanjirou truly wondered how that came to be. How was it that the Kamado family became intertwined with demons and demon slayers.

Heeding Kagaya's words, Tanjirou finally drew the sword. For a long moment, he stared at his own reflection in the steel blade, at least until it started to change color. Slowly, the blade turned black— pitch black, from hilt to tip, as if it was absorbing the light from all around it. Tanjirou frowned.

"Black, huh. You don't see this pitch-black too often," Urokodaki commented.

"A fine color," Kagaya replied. "I'm sure this blade will serve you well."

Tanjirou sheathed his blade and bowed to Kagaya, trying to express his gratitude through gestures alone. Kagaya merely smiled his serene smile once again, and Tanjirou had to wonder what was going on in his head. His reasons for giving Tanjirou his own blade, why he's even helping them in the first place. Even though Tanjirou was a demon… his grip on his blade tightened. He supposed he's a special, valuable demon. One that could help the Corps bring down Kibutsuji Muzan. Still, even if Kagaya's help was possibly riddled with personal agendas, Tanjirou was grateful.

That was when he heard something swoop in from the window. A Kasugai Crow, he realized. It promptly settled on Kagaya's shoulder, pecking at his finger affectionately. Tanjirou had encountered some Kasugai Crows in his time in Mt. Sagiri, as Urokodaki sometimes uses them to send and receive messages. When it opened its mouth and talked, the demon wasn't even surprised.

"Asakusa, Tokyo! Find Tamayo-san!"

"There you are," Kagaya said fondly, before facing Nezuko and Tanjirou once again. "This would be your Kasugai Crow, Nezuko. He will guide you on your way to Asakusa. Take care of him. He is a very intelligent bird."

"Yes," Nezuko replied, lifting her arm to offer it to the bird. The Kasugai Crow flew on cue and landed on her arm, letting another squawk before repeating its lines: "Asakusa, Tokyo! Find Tamayo-san!"

"I must get going, unfortunately. You two will do your best on your first mission, I hope?" Kagaya asked.

"Yes!" Nezuko replied enthusiastically. Tanjirou nodded fervently.

"That's good," Kagaya smiled. "I wish you two the very best."

Taisho Secret: Kagaya truly only decided to give Tanjirou a nichirin sword after he saw that he has what looks to be a demon slayer mark on his forehead. On the other hand, the inspiration for Nezuko's sword motif is from the leafy vine marks that appear on her skin when she's in her final, matured demon form in canon.