Kibutsuji Muzan's Fury!

Anos: "If there's nothing else, I will continue on with my journey."

-------(Scene Break!)---------

Kibutsuji Muzan's POV:

I had been doing some experiments within the infinity castle hoping to find a solution to my vulnerability against sunlight. I had sent out all the 12 demon moons in order to hunt down the Hashira whom Douma claimed achieved speeds rivaling my own.

And it was just around Dusk when I noticed something interesting. My right hand man and most powerful demon Upper Moon 1 Kokushibo had encountered a strange individual who felt nothing like a human. Using my ability to see through the eyes of those with whom I've shared my blood with, I look through Kokushibo's eye's before muttering to myself.

Muzan: "What is this foreboding feeling I have? I-Is this fear?"

My attention was brought back as the two began conversing with each other. And he even had the audacity to insult me! This foolish demon thinks that he is even worthy to insult me! Perfection itself!

Muzan: "It seems they've finally begun to fight.... And what's this?! He's keeping up with Kokushibo?! This is slightly worrying, if this is just his blood demon art allowing him to fight against Kokushibo, then I wouldn't have to worry as much. However, it seems like he hasn't even used his own blood demon art. Anos Voldigoad, where did you achieve such power?"

Muzan's eyes widened as he witnessed something that both shocked and irritated him. A demon who uses breathing techniques.

Muzan: "Not only is he physically superior to Kokushibo, he's also superior in fighting techniques. He may be more of a nuisance then I anticipated. Not only is he more skillful than Kokushibo, he's even able to use multiple breathing techniques at the same time. Thankfully he isn't in possession of that accursed breathing technique. Sun Breathing."

Muzan gasped slightly as the scar's burnt into his flesh from the monster that was Yoriichi throbbed in agony. A scar that even 400 year's after their battle still burns his flesh to this day. Muzan gritted his teeth as he forced those old scar's to stop throbbing in agony as he paid attention to the fight between the two demons. Muzan frowned in confusion and worry as he saw Anos decapitate Kokushibo faster than he could react. However...

Muzan: "I still feel my connection with him, so the blade in his hands isn't a nichirin blade. Does he perhaps not know the weakness of Demons? Unlikely, it's impossible to be this strong and not know the weakness of my demons. To achieve such a level of power must mean 1 of two things. First, he only became like this due to his blood demon art, or he's been a demon for just as long if not longer than even me."

Muzan frowned as his expression became one of confusion as Anos stopped an Axe from trying to decapitate Kokushibo. And he finally got a look at all the current Hashira's and their Tsugokus. Muzan scoffed at them as he all but growled

Muzan: "As expected, weaklings all of them! Having to rely on cheap tactics to try and get rid off my upper moon demon's. But, why did Anos save Kokushibo? Is he possibly trying to recruit him for his own army? And, it seems like this demon even has a connection with the demon slayer corps."

Muzan suddenly remembered how at the beginning before their fight he was indeed trying to recruit Kokushibo, only to get rejected and that this battle only happend because Anos had insulted Muzan's name. A smile etched itself onto Muzan's face as he spoke to no one.

Muzan: "As expected of my right hand and strongest soldier, loyalty only to me."

Muzan continued watching before he heard something rather worrying.

Muzan: "Realm of emptiness?"

That was when a horrifying feeling appeared once more. A feeling that only one person he has ever seen this happen with. Muzan roared in agony as the old wounds resurfaced and throbbed even harder than before as if the presence of a swordsman who has reached the pinnacle has caused the wounds to react.

Muzan: "AGHHHHHH!!!!! YORICHIIII!!! EVEN IN DEATH YOU STILL CAUSE ME PAIN!!!"

Muzan roared in agony before he finally managed to surpress the pain as he began huffing exhaustion marring his expression. Muzan ignored his exhaustion as he continues watching their battle continued for hours more. Muzan then realised that the sun was already rising, and it seems like Kokushibo did as well as he wanted to escape. However, what happened next caused Muzan to freak out slightly.

Anos: "Who gave you permission to leave?"

(Dadum! Boom!)

A horrible pressure fell upon not just Kokushibo, but Muzan as well. And as the Sun had finally risen, Muzan stood frozen and the next second, every single demon carrying Muzan's blood within them felt it. The horrifying pressure of their leader. They all shuddered in shock, confusion, and fear wondering what has just happened. However, the demon progenitor himself, was smiling! A smile that stretched so wide it ripped his flesh and turned into a demonic looking Cheshire grin as veins pulsed all across his body, trembling in joy as he all but yelled.

Muzan: "FINALLY! THE MISSING PIECE OF THE PUZZLE THAT I'VE BEEN SEARCHING FOR THE LAST 1000 YEARS! YOU'VE MADE ME PROUD UPPER MOON 1! NOW LET ME DEVOUR YOU TO ACHIEVE MY PERFECTION! NAKIME!"

The biwa demon nodded her head and strummed her biwa, yet.... nothing happened. The biwa demons single eye widened in shock as she strum her biwa again... Again! AGAIN! AND AGAIN! AND AGAIN! Yet the Upper Moon One never appeared. Irritated, Muzan glared at the biwa playing demon as he sliced her head off, holding the decapitated head before his slitted plum red eyes that was glaring at her with anger as he spoke.

Muzan: "NAKIME! Why hasn't Upper 1 returned to the infinity castle?!"

The Biwa demon Nakime didn't answer for several seconds before speaking.

Nakime: "Forgive me my lord, but I am unable to use my blood demon art to bring back Upper Moon 1. Something is stopping me, and I'm assuming it's whoever he's fighting."

Muzan all but growled before throwing the decapitated head with so much strength it blew up the moment it came into contact with the walls. Nakime regenerated and simply remained silent as Muzan's anger continued rising.

Muzan: "USELESS ALL OF YOU! FOR THE PAST 1000 YEARS NOT A SINGLE ONE OF YOU HAVE SO MUCH AS TOUCHED A STRAND OF HAIR ON THE UBUYASHIKI FAMILY, FAILED TO FIND ME THE BLUE SPIDER LILY'S, AND NOW YOU CAN'T EVEN DO THE ONE THING YOUR USEFUL FOR!"

Tentacles sprouted from across his body as he used his blood demon art Biokenisis. He started thrashing everything around him in his rage. And Muzan would've continued his rampage if not for a voice that spoke up drawing his attention. It was the voice of Anos Voldigoad whose eyes penetrated the entire fortress his gaze landing upon Muzan as he heard the demon spoke.

Anos: Anos: "Did you think I'd allow something as insignificant and weak as the sun to burn this mighty warrior? And... Who gave you permission to try and take him away?"

Crimson plum eye's that spoke of a leader to a terrifying legion of unkillable demons, glared with murderous intent as it met Crimson eye's that brought destruction come all who dare challenge them. And just as fast as the two demons of different origin meet face to face for the first time, it ended just as quickly as Anos ignored him and focused on Kokushibo as within the infinity castle before the horrified eye of the only other demon within the fortress Nakime, her leaders blood stained the castle crimson with the stench of iron permeating it's halls.

Nakime looked on in horror as her master wasn't regenerating at all! She could still feel her connection to him, but he wasn't regenerating at all. Finally when Nakime realised that the battle between Upper Moon 1 and the other Demon had ended, did her master finally regenerate. However, the expression etched on his face horrified Nakime.

Ḁ̶̮̗̿̔N̵͍̦̄Ḯ̷̖ͅM̷̝̗͗͛Ó̶̙͇̒͐S̶̡̪͈̓Ȋ̴̪̪͓́T̸̘̱̐Y̶͈̟̑̎̆

Bloodlust rooled off him in waves that the biwa demon could physically see! She saw an illusion where the corpses of thousands of humans and demons alike with Muzan standing above them all with an endless river of blood flowing around him. In order to save herself from her masters potential wrath, she strummed her biwa once more, and the Upper Moon 1 had appeared within the infinity fortress. The moment he appeared, he was sliced at a speed beyond what the two could even react to before blowing up into chunks of flesh and gore.

Muzan: "YOU FAILED ME! YOU ALLOWED YOURSELF TO BOW YOUR HEAD TO ANOTHER DEMON?! GRRR!!! AGGGGGGGGGHHHHHHH!!!!! DAM HIM!!! DAM THAT DEMON! HOW DARE HE?! I AM PERFECTION INCARNATE!!!! HOW DARE HE!!!!"

Kokushibo who had regenerated already said nothing but stood next to the Biwa demon. Both watching their leaders act of aggression to his surroundings. And the only thought that went through the minds of the three demons watching were.

Anos/Kokushibo/Nakime: 'Pathetic'

And though Muzan should have been able to hear the thoughts of his own demons, Anos had granted them this one mercy by allowing the to speak their honest thoughts without worry for the consequences.

Anos looked at the situation with disdain. To act with such pathetic behavior just because you were killed when you are already immortal was just sad. The two girls who were forced to accompany Anos with his walk noticed his look of disdain as Kanae spoke.

Kanae: "Ano... Voldigoad-San, did something happen? Your face has so much disdain upon it I'm kinda curious what happened to make you have such an expression."

Anos: "It's nothing of importance. Just watching an adult throw a temper tantrum like a child especially with all that power."

Shinobu/Kanae: "Huh?"

Anos ignored their confused look before his eye's landed upon a frail sickly looking old man who was selling charcoal to the villagers. Anos's mouth curled up slightly as he approached the man who was also looking directly at him. The moment he arrived before the young man he spoke up.

Anos: "Hello there Tanjuro Kamado. Nice to meet you."

{Next Chapter: "The Kamado Family!"}