A/N: Here's the next chapter! *hides and waits eagerly for feedback*

Chapter Nine: Final Selection

The days continued on with Nezuko somehow training even harder, so hard that Tanjirou was often worried she was pushing herself too much. She was up even before the sun rose— doing push-ups, swinging the sword, burying her face in a basin of water to hold her breathing— and in the evenings she would go back home all messed up and looking severely frustrated, having exhausted herself with trying to slice the boulder over and over. Even then, the two of them would still fight until midnight, sparring with their wooden swords and pushing each other to the limit of their abilities, improving in small increments over time with every bad habit they discovered and corrected over the months.

As Nezuko improved, Tanjirou did as well— he had started to take advantage of that thing he dubbed the "opening thread", trying to make the most of it every time he detected it. Sometimes he defeated Nezuko with it, sometimes he did not. After all, Nezuko was growing into a wonderful swordswoman in her own right. Tanjirou couldn't help but be proud of her, and from the smell that sometimes lingered on Urokodaki, he was proud of her, too.

Tanjirou knew the day he was dreading was going to come soon. The day when Nezuko would be able to slice the boulder, the day she would finally get approved to go through the life-threatening Final Selection. When that happens, Tanjirou would not be there to protect her. When that happens, their life of peaceful training at Mt. Sagiri would end too, replaced by a life of continuous demon slaying, and Tanjirou was not looking forward to it. Still, it was something that had to happen, if they were to push through their goals of killing that monster and finding a cure for Tanjirou. This extended training montage was merely an interlude to the play that was their lives, and one day they would have to continue on to the next act.

Months passed, and Tanjirou waited. The seasons came and went. Nezuko became stronger and stronger. And when the day arrived, Nezuko came back home with the widest grin he had ever seen on her face, happiness leaking off her as she engulfed Tanjirou in a big hug.

"I did it, Onii-chan! I did it!"

Despite being overcome with worry, Tanjirou could not be any prouder. He looked at Urokodaki, who was staring at the two of them from the doorway. There was a scent of worry on him as well underneath the pride. Tanjirou's chest felt so warm at the thought that their mentor cared about them so much. He gave Urokodaki a grateful smile.

That night, they celebrated with a hot pot, as per usual in this house whenever there was a special occasion. Nezuko thanked Urokodaki solemnly for all the help he had given them thus far, and dug into the food with renewed fervor. Tanjirou contented himself with smiling at them as they both ate their fill, having already taken his vial of blood a few days before. As it turned out, he could subsist on a minimum of a vial of blood every week— anything less would have his body wanting to shut down completely. They have not tested it, but Urokodaki speculated that if Tanjirou ever got injured, he would need to drink more. That's one reason to not abuse his regenerative capabilities, Tanjirou supposed. Even though he had the capacity to heal from even the direst of injuries, he should still take care not to get hurt too badly, lest he lose control of himself.

The night was filled with warmth and laughter. After dinner, Nezuko ended up having to snip off her hair, as she complained that it was already getting longer. Even then, Tanjirou caught her staring at the locks she had cut off with something akin to longing, and it left a bad taste in Tanjirou's mouth. He knew Nezuko liked her hair longer. He hoped she'd let it grow again soon. But he suspected there was something more to it that Nezuko wasn't telling him, some meaning to the length of her hair that she kept in the privacy of her own mind. Tanjirou decided not to pry.

The next morning came too fast, too soon. Suddenly, Nezuko was already getting ready to head off to Mt. Fujikasane, for the Final Selection. The demon boy watched as his sister donned a cloud-patterned jinbei-style kimono, similar to the one Urokodaki always wore, as well as a fox-style warding mask that their mentor had given her the night before. Urokodaki said that the mask was charged with a spell to protect her from harm, and Tanjirou dearly hoped that it would work from the bottom of his heart. All he wanted was his sister to get back to them safely.

Nezuko had a determined look on her face, the same fire burning in her eyes, a nichirin blade strapped to her waist— she looked every way like a fierce fighter that Tanjirou could not help but compare to how she looked merely two years before: fragile, delicate, soft. There was nothing soft about today's Kamado Nezuko, not anymore— except perhaps the way she smiled. She still retained that patient, loving smile that Tanjirou loved so much. It was on her face right now, as she patted his head gently, reassuring him.

"I'm going to be alright, Onii-chan. I'll pass and become a demon slayer. I'll do my best."

Tanjirou nodded slowly as he reached over to straighten her kimono. With the two years that had passed, Nezuko had grown taller. They were almost the same height now, especially with Tanjirou's body not aging after his demonification. It made him sad to think that she might outgrow him soon.

"Mt. Fujikasane is a long way from here, so I don't know when I'll get back. I would like to watch Onii-chan's Hinokami Kagura this year too, but in case I can't, pray for my success to Hinokami-sama for me, could you, Onii-chan?"

Tanjirou nodded vigorously. He would pray to the gods, however long they wanted him to.

"And don't get too caught up in your dancing too, Onii-chan! Pay attention to the sun! We don't want last year to happen again, do we?"

Tanjirou smiled at her sheepishly. Last year on New Year's Eve, he had danced the Hinokami Kagura as soon as the sun set, as per tradition. At the time, he had already pretty much ingrained all the forms into his body from sparring with Nezuko, as well as mastered the breathing technique he needed to keep going. He had managed to dance for hours, getting so lost in his own head that he did not even notice the sun rising, and Nezuko had to cover him up with a thick blanket and pull him back into the house before he got burned. It was so embarrassing, but he couldn't help it. Sometimes the Hinokami Kagura just puts him in a sort of trance-like state, where nothing else mattered but the imaginary beat in his head and the movements he needed to perform through them. Nezuko wouldn't understand— she had never shown interest in learning the Hinokami Kagura before. She didn't know how it felt to perform it. Tanjirou couldn't explain the feeling, either. So in the end, he had let Nezuko berate him for his recklessness, nodding apologetically every few seconds.

Tanjirou lifted up his hand to Nezuko now, showing off his pinky. The gesture was heavy with implication, a culmination of all the promises that the siblings want to keep for each other until the day Nezuko comes back. Promise you'll take care of yourself. Promise you'll be safe. Promise you'll be okay. This would be the first time they would be apart since the day their family was murdered, since the day Tanjirou had been turned into a demon. Tanjirou knew Nezuko must be filled with nerves. He was, too.

Nezuko smiled as she lifted her pinky as well and curled it around Tanjirou's. They moved their hands, their thumbs touching, sealing the promise. Nezuko then let go and smiled at Urokodaki who was in the corner, watching them. Urokodaki walked closer to place a hand on Nezuko's shoulder, a small encouraging gesture.

"Don't worry about your brother. I'll take good care of him," Urokodaki reassured Nezuko.

"Thank you very much," Nezuko with a small bow. She walked out of the house and into the sunshine, before looking back and raising her hand in farewell. "I'm off, Urokodaki-san, Onii-chan!"

"Mmm, mmmmm!" was all Tanjirou could say, but he needed no words with Nezuko. Nezuko understood. All the things Tanjirou could not say, all the things he could not express. Even with mere noises like these, Nezuko understood.

"I love you, too, Onii-chan!" she called out, her voice filled with mirth and laughter. And with that, she ran off, hand on her katana, her kimono swaying with the wind as her form became smaller and smaller in the growing distance. Tanjirou was left with a pang in his heart, worry eating at his insides. He felt Urokodaki place his hand on his shoulder too, and he looked up, his expression slightly helpless.

"Don't look like that," Urokodaki softly scolded. "Your sister is going to be just fine."

Tanjirou nodded, gazing back into the road his sister had taken. And then, silently, he closed the door.

Nezuko is strong, he told himself, his pinky finger tingling with the weight of their shared promise. Nezuko will be alright.

Days passed.

Urokodaki was a man of few words, and with Tanjirou's muteness, the days inside the house quickly became silent and monotone. With nothing much to do, Tanjirou had taken to fashioning his sister's favorite kimono into a haori, for when she comes back with her demon slayer uniform. It has also become his encouragement to himself that she will come back, that she will need this haori someday. Sewing was not his strongest suit, but he worked hard to make the stitches as even as possible, so that it would look as good as Nezuko would have done. He hoped it would be a nice surprise.

At night, Tanjirou continued doing his nightly drills— swinging his sword, controlling his breathing, practicing his forms. It was all he could do not to succumb to the overwhelming worry that hits him whenever he thinks about where Nezuko could possibly be at that moment. Was she still on the way to Mt. Fujikasane, or had the Final Selection already started? Had she already killed her first demon, or did the demon got to her first? He hoped she wasn't tired, or injured, or starving. What if… what if she was already dead? All these thoughts flit around in Tanjirou's mind, and he couldn't help but wish she was back sooner. It didn't even matter to Tanjirou if she passed the test or not, if she became a demon slayer or not— all he wanted was for her to be alive. That was the wish he fervently prayed for every night, and when the New Years Eve came around once again, it was the wish he prayed for to the Hinokami.

That New Year's Eve, Tanjirou danced with a heavy heart. He danced like he had never danced before, putting his all into the movements, into his prayers. Please keep Nezuko safe, he thought as he moved around fluidly, slashing the sword he was holding to and fro. Urokodaki was somewhere else, inside the house maybe. Tanjirou did not care much. He was completely in his own world. He twisted and turned and jumped and leaped, showing off the forms he had practiced with Nezuko so many times in the past two years. The Hinokami Kagura, as he was starting to realize, had become something more than a tradition to him, it had become not only a connection to his family but also a connection to Nezuko in particular, as the memories of them training together poured into his mind. He continued on dancing, restarting the cycle over and over, like a sun rising and setting, like the seasons coming and going— he continued without pausing, seemingly forever.

"Tanjirou," he heard Urokodaki call him from somewhere, but he ignored it. He kept his eyes closed under the face covering, focusing solely on his movements as he danced, over and over. As he prayed.

Please keep Nezuko safe. Please keep Nezuko safe. Please keep Nezuko safe, he thought insistently. If nothing else, Hinokami-sama, even if you weren't able to prevent the deaths of Mom, Takeo, Hanako, Shigeru, Rokuta… if nothing else, I just ask this one thing, please, please—

"Tanjirou."

Keep Nezuko safe! She is the only family I've got! Even if I have to keep dancing forever, please—

"Tanjirou!"

— don't take anyone else from me.

"Onii-chan!"

Tanjirou opened his eyes at the sound of her voice, immediately turning his head towards it, his movement coming to a halt. Right there, beside Urokodaki, Nezuko stood looking worse for wear, her kimono dirty and slashed in places, the warding mask on the side of her head chipped and filled with scratches, holding a walking stick that she seemed to be supporting herself on. At first, Tanjirou's mind stuttered. He had been thinking so hard about Nezuko, that he couldn't quite comprehend that she was standing right in front of him. She did say that she was hoping to see his Hinokami Kagura tonight, that she would try to hurry.

The sword fell to the ground from Tanjirou's limp hands. He wanted to hurry over to envelop Nezuko into a tight hug, to express his utter happiness in seeing her again, but something in her expression stopped him. She was staring at him in disbelief, in awe, and beside her Urokodaki stood motionless, staring at Tanjirou as well, as if there was something even more important and noteworthy than the fact that Nezuko came back to them finally. He stared back to them and tilted his head, questioningly.

"O-Onii-chan, you're…" Nezuko looked up. Tanjirou followed her gaze. It was only then that he realized it, realized that the sky above him was no longer the dark indigo he was used to, but the brilliant blue of a slowly brightening sky. The kind of sky he had not been under in years, the kind of sky that had forsaken his kind. Nezuko looked shocked. Urokodaki seemed to be, as well. Tanjirou didn't know what to think, as he reached his hand up to the sky in wonder, watching the sunlight dance across his fingertips.

And Tanjirou stood, motionless, under the rays of the rising sun.

I hope this letter finds you well, Oyakata-sama.

I will not bother with pleasantries, so as not to waste your precious time. Two years ago, Tomioka Giyuu had sent to me a pair of siblings he had met while out on a mission. It was a girl who wanted to become a demon slayer, Kamado Nezuko, and her older brother, Kamado Tanjirou. As is the unfortunate usual in a demon slayer's line of work, the siblings had just gone through a personal tragedy. Their entire family has been slaughtered by what we assume is Kibutsuji Muzan himself, and Tanjirou, subsequently, has been turned into a demon. Despite losing his humanity however, Tanjirou had not lost his human emotions. Even in a starved state, he refuses to devour humans, subsisting merely on a small amount of human blood. Even now, two years later, this has held true. Tanjirou is a remarkable kid with a remarkable sense of self-control. But I digress.

A month after I took them in, I found out that the Kamado siblings somehow had demon slayer heritage in their blood, a fact that neither of them was aware of in the beginning. On the eve of the New Years, Tanjirou performs a family tradition that they called the Hinokami Kagura, and it turned out to be a breathing form that Tanjirou later identified as Sun Breathing. I believe this heritage may be the reason that their family was attacked to begin with, and I had decided to look into it. But now, two years later, I remain unable to find anything about a Sun Breathing Form. Thus, I have decided to reach out to you, in hopes that you may be able to shed some light on the subject.

I believe their demon slayer heritage and this mysterious Sun Breathing Form is connected to the multitude of eccentricities I have seen on Tanjirou. He is a unique demon, unlike anything I have ever seen before. Not only had he conquered his hunger for human flesh, he had also recently conquered the sun, and right now was able to walk under it without any issue. Although the situation seems far-fetched, I assure you that it is an indisputable fact. While I worry about what a sun-resistant demon may mean to the future of the Demon Slayer Corps and the demons at large, I have to admit that Nezuko and Tanjirou had become somewhat dear to my heart. Still, I am not letting my fondness cloud my judgement when I say that I am confident that Tanjirou would not bring any harm to humans, nor would he aid the demons. He is a trustworthy person, and in the event that he proves to be otherwise, Kamado Nezuko, as well as Urokodaki Sakonji and Tomioka Giyuu, will atone by committing seppuku.

Now that Kamado Nezuko has passed the Final Selection, Tanjirou wishes to accompany her in her missions. I sincerely hope that you will allow it. These siblings have no one else but each other, and they are both powerful swordsmen in their own right, as I have trained Nezuko in Water Breathing, and Tanjirou had developed the Hinokami Kagura. I believe they will manage to save and protect many people, and become a force to be reckoned with. This is just my gut feeling, but I think Nezuko and Tanjirou would be a vital component in our never-ending fight against Kibutsuji Muzan. Perhaps they will make a difference in our quest to end the demons once and for all.

Thank you for taking the time to read this letter. I wish you all the best in your endeavors.

Yours truly, Urokodaki Sakonji.

Taisho Secret: In canon, Tanjirou became resistant to the sun almost immediately after he got turned into a demon. This author headcanons that it's because he has been using the Breath of the Sun for quite some time. That headcanon applies to this AU, and Tanjirou ended up conquering the sun way faster than Nezuko did. On the other hand, Nezuko did defeat the Hand Demon in the Final Selection. Good job, Nezuko!