Chapter Text
Feeling the disgusting burn in his veins and slight throbbing from his brains as he walked up the base of Mount Fujikasane, Muzan Kibutsuji began having second thoughts about this spur of the moment plan of his. The sensation of being ill once more…why he could level this whole mountain right now for making him remember it.
Yet, he persisted. He was not the King of Demons for nothing. It was a vile sensation but he would live, and he would see this plan - this massacre - through.
It had been Gyokko that had spurred this trip. Upper Five had reported back to Muzan, with no information on the location of the Blue Spider Lily nor the headquarters of the Demon Slayer Corp. Oh but what juicy intel he discovered regarding the latter.
“I saw it with my own eyes, Lord Muzan. Kin of the Ubuyashiki family, guided west toward Mount Fujikasane. No bodyguards in sight! Oh, Lord Muzan, believe me, I would have continued to follow them but the base of the mountain was filled to the brim with Wisteria - but I just had to report it to you!”
While the location of the Ubuyashiki’s residence alluded him, what importance Mount Fujikasane had to the Corp did not. After all, when he noticed so many demons gathered in one place it raised concerns of his demons breaking his rules.
The Final Selection, he believed it was called.
Its name did not matter, but its purpose was clear - several demons rounded up, trapped in the confines of that mountain for children to see if they qualified to join the Corp. When Muzan made the discovery centuries ago all he felt was disappointment in his demons. He did not offer them a quick death even if some were trapped for years. If those demons were weak enough to be captured and transported, to be used as nothing more than practice, then those demons deserved their fate.
Now he felt something he did not like feeling. Unyielding rage.
The family he spent so many years, so many demons, so many resources looking for was just off toiling around with no protection for what? To see humans that will inevitably die kill some inadequate demons? That was the reason for this family to leave their sanctuary? They weren’t even powerful like they were in the Sengoku Period. If anything they were woefully pathetic now. He could tell from the amount of lower demons, begging and pleading their case to become one of the Twelve Kizuki. Acting like killing dozens of pathetic slayers justified them asking for more of his blood.
If the Ubuyashiki family wanted to oversee this test, of sniffling brats dreaming too high with too little time on this earth going up against his mistakes of demons, then Muzan would give them something to see.
The burning sensation had finally subsided and the little nausea the flowers had made him feel evaporated - he was now at the mountaintop.
He could already hear high pitched screams, a sound he was all too familiar with. The test had already begun and his demons were now fighting for food. He headed toward the sound, his first stop on this busy night.
While he could rush over there in an instant if he wanted to, the King of Demons chose not to. He did not want to make his presence known, at least not yet anyways. Also, in an occasion that was becoming rarer for his millennia of living, Muzan got to see an area he had not come across before. The air here was slightly thin and the wisteria below helped illuminate the dark night, making it easier to see - probably another reason why this was the location of the examination. It truly was a lovely place and it would look even better once covered in blood.
Despite the ground being littered with twigs and loose rocks, things he had stepped on that should have alerted the demon he had made his way to, it did not notice Muzan approaching. It was too focused on eating one of the examinees. The human could not find their voice as the large demon used one of the many hands that covered its body to grab them by the ankle and brought them to its mouth. Only sniffles and whimpers came out of the pitiful child, too scared to fight back when confronted with death, as they were lowered into the demon’s mouth and swallowed whole.
“Have you finished your meal? I’ll be honest, it didn’t look very appetizing.”
The demon covered in hands finally noticed its Master standing by it. Its eyes widened and while it seemed to struggle with its large frame, it had managed to lower itself and bowed before Muzan.
“I-is that really you, Master?” The demon dare not look up. At least it knew its place. “Wh-why are you here? If there is anything I can do to assist you-”
The hand demon did not finish its sentence, it was dead before it could finish. Its body exploded in an instant, its remains covered the ground and trees.
That demon may have known to not look at him, but being captured and trapped on this mountain by slayers made it worthless. It did not even have the right to speak to Muzan after doing nothing of note with his blood.
“Muzan Kibutsuji!!” A voice roared behind him.
How curious, a baby slayer knew his name. And his face. Must have become a slayer to avenge someone after he killed or turned someone. Muzan turned to face the slayer in-training.
It was a boy, who couldn't be any older than sixteen, wearing a blue, cloud pattern kimono. His face, however, is what stood out. Or, lack thereof. The boy was wearing a warding mask that resembled a kitsune with a sun on its upper right forehead that covered his facial features. A charm most likely given to the boy to protect him from harm.
How unfortunate that it didn’t work.
“You’re going to pay for all the people you’ve killed!” The boy raised his sword, to perform one of his Breathing techniques most likely, but Muzan couldn’t be bothered to tell what style it was. His moments were too slow, his grip on his sword too weak, his footing not centered.
His demons were right. The Corp’s recruits have gotten worse in quality.
Oh well. It doesn’t matter. This boy shall be the first.
In a blink of an eye, Muzan was behind the masked boy. The boy’s body was only starting to react, a slight tensing of his shoulders, when he scratched the back of his neck. With that, he did not give the boy another glance, but he did offer some final words to the potential demon should he withstand his blood.
“I hope you enjoyed saying my name, it will be the last time you’re allowed to say it…that is if you manage to survive.”
The remainder of the night went in a similar fashion. Find an examinee, give them a drop of his blood with a scratch and move onto the next. None left an impression on him nor did any recognize him like the boy in the mask. They blurred together. A girl in a pink kimono, a boy in a yellow-spotted haori, a boy in a purple yukata. He forgot them the moment after he infected them. If they could not withstand his blood he would have been none the wiser. The random boar he had spotted in the distance left a longer lasting impact on Muzan’s memory of the night than any of the children.
Confused screams echoed through the night, at least some of the children who had turned had found other examinees before he did. The massacre had finally begun. The only task left for him was to find the Ubuyashiki offspring and have them deliver a message to the current head of house.
For their protection they would probably be near or past the field of wisteria so none of the progeny got accidentally killed by a demon while the exam took place, how annoying. Muzan supposed he could wait another night to deliver the message. He was in no rush, all his personas that masked his true identity did not need his attention right away and even if one did, starting from scratch again and creating a new web of connections to help locate the Blue Spider Lily was no issue. He might even do that after this since his Upper Moons seem to be failing miserably at the task.
He found shelter in a makeshift cave, no doubt created by one of the demons that managed to survive on the mountain for a long period of time. It was poor sleeping accommodations, another reason for him to curse his weakness to the sun and those pesky flowers. Laying on the hard rock was almost enough to make him abandon the pursuit, but he had already come so far with it. If the Demon Slayer Corp realizes that there will be no new members for the season, no help coming in the distance, then he wanted them to know it was him who caused it and if the Ubuyashiki wanted to leave their secure, safe hideaway that still alludes him they need to know that decision comes with knowledge that Muzan will find them.
As he retreated into the cave with the sun just over the horizon, Muzan heard some rustling from the bushes nearby. He didn’t sense a demon - did he miss a candidate?
Its head poked up from the bushes and ran away from him, it was a boar again. Animals, Muzan had come to find, had better instincts than humans. They knew the power he held just by feeling the air around him, and knew to avoid him if they valued their lives. This one was no exception.
A boar was not worth the risk of the sunlight. Animals were harder to control as demons, more likely to grab attention from authorities with their carnage, easier for slayers to willingly kill.
A single boar living would not make a difference.
Inosuke Hashibira was not a quitter and he certainly wasn’t a coward.
Was that demon in the nice suit powerful? Yes. And was he so powerful that just being around him made Inosuke’s skin crawl and made every single cell in body scream ‘run’? …Also yes. But Inosuke didn’t become Lord of the Mountain for nothing! He laughed at those who thought they were stronger than him.
So while, yes, Inosuke ran away temporarily, and yes he did leave the mountain after reporting to those two tiny kids at the base of the mountain since the seven days were completed, and yes he forgot to tell them about the powerful demon because they told him he’s getting his own swords soon, none of that means anything! Cause he’d just kill that demon now and prove he was, in fact, the strongest on Mount Fujikasane.
Then he would be the Lord of the Mountain of two mountains. Easy.
He waited till sunset to run past the field of wisteria flowers. The mountain was huge and Inosuke couldn’t risk not finding the demon or having the sun claim victory for him. No, that demon’s head would be cut off by his (stolen) swords and no other way.
It was quieter on the mountain than it had been the night before. That last night was very odd, first that super strong demon, then all screaming reached the loudest it had been in the week that they were there. Inosuke even swore a demon he killed last night had a nichirin sword on them. Did it manage to pick one off of other candidates? It wouldn’t be that surprising, he also stole the swords he was using.
He sprinted through the mountain as fast as he could and still felt no skin crawling energy. He was getting frustrated. Where did the super strong demon go? It didn’t just leave right?
In the distance, Inosuke finally saw a demon. It was not the one he was looking for. No, this one was a girl maybe around his age. Her pink kimono had some tears on it, like someone was clawing at her, her mouth and chin were stained with dry blood. Attached to her hip was a sword that had a flower-like handguard. Most off putting thing about her though was the fact she was just standing there. Her slitted eyes seemed to be staring at nothing and not blinking. If it wasn’t for the heavy breaths that came out as low growls, Inosuke would assume she was dead.
Inosuke did not know much about the rules to demon slaying or its corps, but going straight for a demon’s head after encountering one seemed like the right idea. He should kill her right now, she wasn’t moving, it’d be very easy. But-
“Hey demon!” He shouted as he came into her peripheral vision. It got her attention, her eyes that were staring at nothing were now focused on him. “I’ve got a question for ya!”
The demon did not say anything.
He unsheathed one of his swords and pointed it at the girl. “Where’s that super strong demon? Where you guys hiding him?”
The demon blinked and still said nothing.
“The strong guy! The one you can literally feel if he’s around!!”
Silence.
“Answer me, damnit!”
“I do not know the answer to your question,” the demon replied softly.
“Do you know where other strong demons are?” He might as well kill them all while he was here. Then no one could take his title of Lord of Mountain after he leaves.
“I saw some other demons before you arrived. I don’t know if they’re strong or not.”
Oh well. At least he’d get to kill some things tonight. He really should just cut this one’s head off right now yet-
“Do you know where they are?”
“I know where I saw them last. I can’t be sure they’re still there.”
Fuck it might as well try. He pointed both swords at her now. “Show me where they are.”
There was no hesitation or panic. Just an honest answer. “Of course.”
“W-wait are you serious?!” He did not actually think that would work. There’s no malice in the air to make his skin feel gross. No fear that made the air feel sticky. This wasn’t a trick, at least not that he could tell. She was being genuine.
“Yes.”
“Why?!”
“You gave me an order,” she explained as if it was the most obvious thing in the world.
The boar mask stared at the demon girl for a long time. The girl did not say anything to the prolonged silence. She in that moment was acting like a minion that worked for him.
Oh, Inosuke just had the greatest idea.