A pale man wearing a black suit as dark as the night, a whit collar shirt underneath, black long pants and shoes, while wearing a white hat. This man was walking up a mountain that had snow several inches deep. But this did not hinder his movement as he kept walking as if there was no snow that was knee high.

The pale man usually didn't run earns but instead let his underlings do all the hard and dirty work, and usually he would have a calm face. Yet, as he walked up the mountain he had a face of pure anger and frustration. But his frustration started months ago when one of the recently transformed demons had traveled over this very mountain and was killed. The thing is that when a demon dies he would be able to see and hear what they do. And normally he would just ignore this as usual, however when he was about to ignore it completely he saw the individual that killed the demon. A person that wore flaming red and black kimono, with a black nichirin blade, but what really caught his eye was the hanafuda earrings. And before the demon vanished he could hear the person say "I'll be waiting Muzan Kibutsuji."

Without hesitation he had sent two assassins to the very mountain only to get the very same thing, his assassins had been killed and the person said it again "I'll be waiting Muzan Kibutsuji." His frustration has turned into anger as he kept sending lower class demon after demon to kill this man in waves, yet every time they would fight this man that resembled that monster their fights would end in a matter of seconds and he would get the same message.

So he sent one of the lower moons, a lower moon that was accustomed to forest combat, Rui lower moon 5.

———-———-———-———-———-——-

A weeks ago:

Rui hadn't left his mountain for centuries and had remained stagnant with his powers since he started to form his little 'family.'

Rui had skin as pale if not as paper than Muzan's skin, to the point wher it looked as white as snow. He also white hair that covered his left eye and looked to be stuck in a way that expanded away from his head. He wore a white kimono with spider webs that ran through the clothing.

Rui was old, but he still retained the image of a boy and had the mindset of one. Yet he had been misguided and was given a power that he should have had. The power of a demon.

And said child would seem to be floating in the air, but if one were to look closer they would see that he was standing on string. These strings were as strong as steel and was under the control of Rui. Thou while he stood on the wires his head was looking up into the stay, until he felt a sense of overwhelming power that exploded inside of him. This almost causes Rui to fall off, but he was able to make more strings that formed below where his hands would fall.

"Head to this mountain." And suddenly as soon as he heard rose worlds he was shown images of a mountain that would take a few hours at top speed to get there. Some demons would follow this with a smile on their faces as their lord and master commanded them to do his bidding. Rui was not like the common demons, he is a Lower moon, but the blood of their creature's blood coursed through their veins and would force them to comply. So he left without even a word to his 'Family'.

He traveled to the mountain as fast as he could. During his travel he crossed another mountain that had a little house at the top, but he just ignored it as he had a mission and he did not intend to fail. Soon he made it to the mountain foot of the mountain and started to ascend, but as soon as he started to ascend he could feel an overwhelming presence. This felt like something Muzan would creat but the difference was clear and evident. Muzan's presence would insight a cold and dark fear that could freeze a person dead cold, yet this presence emitted an aura that would burn anyone that dared get closer. Even though it was winter and the air could bite ones skin and tear at it this presence made everything feel unbearable hot.

As Rui ascended the mountain the heat was becoming unbearable and he wished to turn back, but his blood would feel as though they would explode out of him if he even dared to descend. So he continued to move up and soon he say something that should have been impossible. At the top of the mountain was a clearing that had flowers blooming everywhere and the grass as green as an emerald and in the middle of this field was a pool of water shaped as a circle and a boulder in the centre of the water that was have submerged. But what was impossible was how hot it seemed to be at the top. It was winter and snow should have been everywhere but the at the top there was none, even the water was steaming and Rui believed that it was due to the person on top of the boulder.

At the top of the boulder was a boy that wore a red haori over an orange kimono with black hakama, but the thing that stood out the most and brought a fear that wasn't Rui's. The boys face and the hanafuda earrings. The face was young, almost as young as Rui's, he had crimson red hair and eyes but what set off this outsider fear was the mark and the earrings that brought back foreign memories. The mark that was on the left side of his forehead and was touching his left eyebrow. And the earrings was a sun shining over the surface of the earth.

"How much do you value life?" Rui finally overcoming this outsider fear, realised that the boy on the boulder was now standing and now he could see a nichirin blade. 'So he is part of that weak organisation that hunts weak demons.' Rui thought as he say the blade was a black colour. "How much do you value life?" The boy spoke again.

Rui didn't respond and instead lashed out at him. He summed five white strings that would cut with enough force to cut a man in half. His strings reached the boys position and it slammed into the boy with enough force that the boulder was cut in six pieces. Yet the boy was no where to be seen. "Why do you kill?"

Rui heard the voice come from behind him and so he jumped forward and twisted his body to lash out five more strings but again the boy was gone. "You kill for food, yet I meet another demon who drinks blood from people that donate their blood, so why kill." Again from behind, the boy had some how the boy had jumped behind him. Rui tried to twist his body to preform another strike but was kicked with enough force to send him flying back to the ground that made a small crater.

The boy had kicked Rui as a way to propel himself so he could land gracefully to the ground. And so as he landed he stayed there and waited for  Rui. "Who are you?" This time Rui said it as he climbed out of his crater. But as he said this he was starting to build up some fear as he, lower moon 5, was being beaten by a kid that hadn't even used his sword.

The boy blushed and rubbed the back of his head with his left hand as he had forgotten his manners, "Forgive me, how rude of me for not introducing myself. My name is-" but before he could say his same five more strings appear and to Rui he was gone in a matter of seconds. One second he was there and the next he was gone. Expecting this creature to appear behind him again he turned around and released his strings again, only to hit air and the trees that surrounded the clearing. "Tanjirou Kamado." Rui suddenly had a dome made of web and string form around him and close in, in quick succession. But the only thing that the strings hit were Rui.

Rui was physically fine, but mentally he was screaming. This beast was not human. No human could possible move that fast. Unless he was a... "hashira." He said unknowingly and soon he would regret it.

"Wrong."

Rui turned around to see this beast standing on the broken boulder. Rui didn't waste time as he used his strings again but this time he infused his blood with them making them ten times stronger. But he didn't attack, he hesitate as he waited for this beast's next move.

"You disappoint me Muzan, I expected you to come and challenge me instead you send others that you had corrupted to do your work. I will wait here for another week, if you send anyone else I will leave this mountain and search for you, then I will kill you. As of right now I merely want to talk." Rui wanted to attack while he was talking again but something was holding him back, as if his blood became solid. But now he was free and he sent all his strings that he had at the monster. Rui thought in his head that this was it, he would kill this monster as it just stood there.

"I am sorry that you were turned into a demon." Yet it was not meant to be as in a blink of an eye the monster was at top of the boulder and then he could hear the voice coming from behind. Then he realised that his neck had been cut off.

His head fell from his body as it also fell. He stared at the sky and beyond it, the stars. But he was filled with anger and confusion, he didn't understand what was going on and he wished for the monster that killed him to die.

Suddenly his vision obscured by the monster's face. Though there was something that made Rui's anger halt. The eyes that Tanjirou held was one of sadness and sympathy. "I do not know what happened in your life that made you become a demon at such a young age, but I hope that you find rest in your afterlife."

And with that Rui felt something that he had not felt in a long time, love. As he died he felt the arm of his dead father and mother embrace him as they traveled through hell.

Present:

And Muzan's anger was because this boy wasn't a hashira and yet killed a lower moon without even using a breathing style. So he called on them and had them do something that would prove if they are worthy of being kept alive. But what really angered him was just how much this boy was trying to imitate that monster. The boy had proven to be fast and could kill demons but had failed to show any breathing style and the blade of the boy's is black. Muzan believed that the boy wasn't any threat as he didn't have a crimson nichirin blade that the monster had. But the threat still loomed ever closer as he thought that if the boy was left to his own and joined the demon slayers, this boy could be trained to become a serous threat. So he took this serous and traveled to the mountain and when he got to the top it was just like it was after Rui's fight.

A boulder sliced in 6 pieces in the middle of a small pond and beyond that was the flowers. And in the light of a full moon it looked beautiful. Thou there was one slightly difference, the boulder that was cut in six pieces was being held together by a large rope. But Muzan didn't care about the scenery, all he is focused on is the boy that stood on top of boulder. "It is finally nice to meet you Muzan." Tanjiro said with a smile on his face.

"I am curious as to why you would wish to meet with me. You took a massive risk in contacting me and yet you still wanted to see me, why?" Muzan said as they were now both wearing stoic face.

"I wanted to know why you kill people and create more demons." Tanjiro said.

"Because your kind is nothing but cattle for us to consume, and why do I create more? It is so I can kill the demon slayers." Muzan said with a smile on his face as he thought that he could provoke the boy into attacking him and therefore allowing for Muzan to kill this kid.

But Tanjiro just stood there, but his face showed signs of sadness. "So I were to offer you a new way of living and a way for you to live your life in peace, you would reject it."

"Yes." Muzan said as soon as Tanjiro finish his sentence.

And in an instant Tanjiro was in a battle stance, his knees bent and both hand holding the nichirin blade in a reverse grip. Upon seeing this stance that resembled that monster's own stance Muzan let loose as he release bone like tentacles that ripped his clothes and waved in the air ready to attack, while Muzan arched his back, bent his knees and had his claws at his side.

Both combatants waited for their counterpart to move first, yet both of them stayed still. The air became heavy, as if gravity had increased. The heat became unbearable to Muzan, but it would seem as though Tanjiro was not affected. Neither of them wanted to move so Muzan snapped his fingers. Suddenly five more demons came out of the forest clearing and rushed at Tanjiro with multiple ability and attacks.

Muzan relaxed a little as he believed that this boy would die here and now. He could see it now as they tore his flesh and grinned his bone, then started to devour his corpse.

"Dance of the sun; first form: flash dance." Muzan's smile appeared as fast as it had disappeared, because as he was perceiving everything is slow motion he noticed the black nichirin blade turned crimson. And as soon as it completed its changing Tanjiro launched into action as his blade released flames and almost becoming a blur to Muzan as he moved so fast that only he could see and follow this boys movements as he cleaved the heads of all the lower moons that he had brought with him.

In less than five seconds all his demons had died and this second coming of the monster was now going straight for Muzan. Without a second thought Muzan ran.

He used his tentacles to act as rope that would grab onto trees and pull himself forward. To a normal human he was going so fast that he would be considered a blur. With his speed he thought that he would be safe. Sadly for him when he looked behind him the monster was still chasing him. Muzan sent some of his appendages to attack Tanjiro and kill him, but really Muzan is trying to slow him down. But even under the constant assault Tanjiro kept coming closer.

Muzan decided to cut the trees behind him to slow him down. The trees did slow down Tanjiro, only slightly. Some would say that it didn't make a difference, but to Muzan it was a massive success. Because it meant that putting objects in his way would slow him down. So Muzan let his tentacles slice any tree that could get in this monsters way.

"Dance of the Sun; Thirteenth form; Sun eclipse." And with that Muzan became horrified as it seemed that his end would come soon. This monster became faster than he could possibly believe. The trees that were getting in his way were now being shredded like pieces of paper. Muzan hadn't truly wanted to escape, but instead try and kill him by using the trees and his higher mobility to kill him. Though once Muzan bared witness to how similar the two monsters are those thoughts disappeared. He used his mental link to a upper moon demon to tell her that he needed a way out.

Though the women tried as fast as she could she is slower than the blade of Tanjiro.

Tanjiro advanced forward with incredible speed that was unrivalled. But soon this would end as this breath style was still new and he could not maintain it for long. And he was running out of time. Tanjiro could feel his lungs shake, his head hurt and his vision becoming blurry. Though that did not stop Tanjiro from getting into striking distance of Muzan. In a span of a second Tanjiro had cut off Muzan's arms, legs tentacles and cut his body in half. Tanjiro felt happy as he was going to end this monster that has taken many lives and ruined many more. But fate had other plans as Muzan disappeared before Tanjiro could land the finishing blow.

In utter disbelief Tanjiro had loss concentration and had fallen unceremoniously onto the snow after tumbling multiple times and hitting a tree. Tanjiro was now sitting and leaning on tree. He failed. He failed. He failed. With those thoughts in his mind he started to cry and blame himself for even giving Muzan a chance to explain his reason for killing. He blamed himself for failing to avenge all the people that have died from that monster. He blamed himself for failing the man that had taught him how to properly use the dance of the fire god. But he knew that he had to keep moving forward and he soon saw arms and legs that he had cut off starting to disappear. Tanjiro acting fast grabbed a knife and threw three of them at the limbs. The knifes landed perfectly onto their targets and started to fill a vial inside of the knives.

"Meow." Tanjiro looked rough his side and saw a black cat with talisman on his forehead and a bag on it's back. Soon the cat grabbed the knives one by one and had Tanjiro put the knives into the bag.

"Meow." And soon the cat disappeared. Tanjiro sat at the tree for a few minutes. While he sat there he looked up at the sky filled with bright dots that littered the night sky. But he then say a black figure in the sky that was blocking the stars. He looked closer and say that it was a crow. Tanjiro ignored the crow as it soon flew away and soon after gathering his breath and went down the mountain and to his home.

Bonus:

Unknown location.

The crow flew in a straight line until it had to take breaks but the crow would continue moving in a straight line as headed to its destination. And soon it reached it. It looked to be a massive Japanese mansion and in the mansion is a garden place and in the middle of it a man stood there.

He wore a white kimono and had black hair but this man looked to have had a burn mark that spread from his forehead to his eyes.

The crow squawked and the man extended his arm. "A boy, name Tanjiro Kamado has encountered Muzan, almost defeated him and has survived with no injuries." The crow spoke to the man. And the man's face showed clear signs of shock. Not from the bird talking it from what the bird had said.

'Someone had managed fight off Muzan and survive, how?' That was the only thing that occupied his mind at the sheer weight of those words brought. This crow had been sent out to investigate why Demons have been travelling there and he had gotten more than he had asked for. Suddenly his shocked turned to one of joy as he said, "Please call my children to come back to headquarters."

Behind the man was a place where cover was that was connected to the mansion. Underneath the cover were two girls that looked to be small and twins but there colour of hair and clothing is different. "Yes, master." The two girls said in unison.

And with that the two girls had went inside the mansion and left the man there. He stood there and whispered something into the crows ears and soon it flew off in the same detection it had came from. The man than said something with a smile on his face, "The war is nearly over."