Not meant to be (Muzan x fem reader)

4 vs 1

"Kaw Kaw! Kamado Tanjiro and Tomioka Giyuu have defeated upper moon 3!" a high pitched voice echoed through the room as you gave a rough kick to the girls sword, flinging it away.
"Sh-shinobu san is dead...?" Haruo mumbled in shock.

With no hesitation, she gave you a punch to the face, scratching you in the process.
"Tch, that kinda hurt," You mumbled wiping off the blood as your wound quickly healed itself like magic.

" But not as much as when that woman stabbed me to death,"  You continued, speeding to the sword to break it into two.

But before you could, Haruo slashed through your abdomen, pinning you do the ground.
"I-I'm so sorry Nee-san," He mumbled under his breath as he held you down, giving enough time for his companion to grab her sword.

You kicked yourself off the ground, prying Haruo and his sword from you.

As he tumbled down, you stood up, eyeing at the two as you abdomen slowly closed itself up.

" Lets make a bet, If I kill you Haruo, I'll make sure to keep your body intact without any missing limbs, so you live peacefully in the afterlife, but if you kill me, then take this thing off my hand and give it to Muzan before he kills you, or if the most impossible scenario where you destroy him, take my ring and keep it for yourself," You blurted out.

"Is this woman mad or something-"
"Deal!" Haruo shouted running towards you

This was definitely going to be a long fight.

.
.
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Kokushibo looked at Muichiro as he observed the boys features.
Genya silently stayed on his knees, observing the two standing at a distance.

" You're one of my offspring aren't you? My child's child," He spoke as Muichiro glared at the six eyed demon.
" W-what? No I'm not!" Muichiro yelled back, getting out his sword.

" You can't deny it, I know it, what was your name again, Muichiro?" He spoke again, pointing at the short boy.

Muichiro clicked his tongue, getting his breathing technique ready.
While he was unable to directly hit anything to Kokushibo, the demon still praised him or his agility at such a young age, seeing the mark appear on his face.

" You are definetly my offspring with such a technique," He added.
"Tch, even if I am your descendent, not a single drop of your blood exists in me I know that," He glared, suddenly calming down.

" Well then, I must take out my sword as well since it will be rather unfair," Kokushibo spoke, sliding out his sword to reveal a unsightly group of eyes surrounding the entire sword.

As Muichiro charged at Kokushibo, the demon chanted a breath. 'Moon breath' and within a second, Muichiro's left arm flew away as blood spurted out.

Muichiro was shocked, how could this be? A demon with a breathing technique? What?!
Muichiro tried to stop the bleeding and continued to charge at the demon, unleashing the techniques he could do, but they were all in vain as Kokushibo somehow got a hold of his sword, banging him to a pillar and pinning him there with Muichiro's own sword, pierced through his shoulder.

" It's best you turn into a demon for your own sake, that way you wont have to worry about these silly wounds. But if that man doesn't except you, you'll die," Kokushibo muttered as he held Muichiro cheek examining his grandchild.

" Well, that just how's your fate of death can't change, isn't that right?" Kokushibo said.

Genya took his sword, silently getting up from his hiding spot.
" I asked, isn't that right?".
The voice echoed through Genya's ear as the demon was now behind him.

How could this be? Of course he is a demon, but this type of speed is shocking.
Kokushibo quickly chopped Genya's arms off, but he didn't really scream about it, in fact, his detached arms were still moving.

" Well this is interesting, another one of you fake demons have appeared,"' Kokushibo spoke as he sliced through Genya's stomach, separating his torso and legs from each other.

Yet he still was alive, moving.
" That's strange, the last time a met a creature like you they died the moment I separated them in half..." Kokushibo mumbled in confusion.

" Oh, maybe you're head is the thing I have to decapitate, wow, your even more like a fake demon, good thing I'm doing a favor for Muzan," He spoke, about to slice of the head until another sword collided with his, pushing him away as a chunk of his hair was sliced off in the middle.

There sat Sanemi in front of his brother, protecting him.
And Genya thought he hated him.

" Shit, why did you even become a demon slayer, you idiot," Sanemi spoke as he eyed his helpless brother on the ground, separated into bits.

"I, I just wanted to help you A-aniki-,"
" Dammit, why didn't you just go get a wife and have some kids or something you dumbass?!" 
Genya stayed there silently, confused at his brother request.
" You could have lived a happy life then, because I would make sure no demon would disturb you,".
.
.
Those two sentences were enough for the younger sibling to shed tears immediately.

"A-aniki..."
" Oh another one has arrived, who are you then," Kokushibo asked as Sanemi looked at the demon, smirking.
" Im the wind, and I'm here to decapitate the head of yours you fucker, how dare you slice up my brother into bits!" He yelled.

"sorry we were late," Gyomei spoke as he took out his weapon, his blind eyes glaring at Kokushibo as the demon stared at him in shock.

"Such a strong physique your have," He mumbled as he saw the inside of Gyomei with his perfect eyes.
Gyomei and Sanemi's marks soon appeared as Kokushibo sighed.

" It's a shame you wont be able to live long now that you have unleashed that mark," He spoke as Gyomei smiled.

"Oh really now?" He replied to the demon.
Kokushibo raised an eyebrow to his reply.

"Wasn't there someone who managed to live over the age of 25 despite having the mark?"

Kokushibo's eyes widen angrily as he remembered the face of his younger brother. Such a face he had.

Within a flash, he sped towards Gyomei as he prevented his attack, slicing Kokushibo's sword in the process.
"It's useless, whatever that is cut shall grow back,"

While the two of them fought, Sanemi joined in, deciding to unleash his 'drug'.
As Kokushibo injured Sanemi, the stench of the white haired man's blood dulled his senses for a while.

" Wow, I did not think it would work on an upper moon, damn!" He shouted excitedly as he clenched his sword.
" You are a Marechi aren't you," Kokushibo muttered.

" What else idiot?! My blood is like alcohol to you pests!"

While the three of them kept Kokushibo occupied, Muichiro managed to pry off the sword and fall down, crawling towards Genya.
" Shit, why am I so weak?! I should at least help Genya," Muichiro groaned as he went next to Genya.

"Genya! Are you okay?" He asked as Genya grunted.
"I'll- B-be fine if you get me that piece of that demons hair, it's right on the floor..!" He replied as Muichiro spotted it.

He sped towards it, grabbing the maroon strands and running back to Genya in pain.
"H-here!"
Genya swallowed the hair  then pointing at the piece of Kokushibo's sword lying on the floor.
"T-that too!"
Muichiro obeyed his words, snatching the metal and feeding it to the armless Genya.

"Argh!Th-thanks!" He mumbled as the sword pierced through his sword, into his stomach.

"Just..give it a moment to work, anyways, listen to my plan Genya, I may not be much help since I'm losing so much blood, but listen," Muichiro whispered.

" Oh I'm listening,".