Y/N POV
As I watched Kaigaku constantly get thrown and put down he kept getting back up while he tried using his breathings on them.
"Y/N,what are you planning to do with him?
He's been fighting them for over sixteen hours now and he's already exhausted."
Mother asked watching the poor boy while I just scoffed in pure amusement smiling on how he already suffered several blows as he tried landing a single hit on one of them.
"I'm trying to make him a living weapon.
One that kills without conscience and with no remorse or even guilt to stop him from killing a person.
Then I'll turn him into a demon as my own assassin to turn the slayers using my blood through him.
Isn't that fascinating?"
I replied noticing the black crack - like veins appearing on his neck making me smile as his eyes are slowly turning black while the others decided to turn up the game a little.
"Blood Demon Art : Wind Slicer."
Sanemi muttered waving his hand down as strong gusts of wind passed us by while three claw marks appeared on Kaigaku's chest injuring him with the attack's force pushing him back.
"Blood Demon Art : Mist of Clouded Memories."
Muichiro answered as the wind became visible while it surrounded only around the boy while Sanemi's attacks can be seen moving in the mist with him constantly swinging his arms.
"Poor boy.
I can't imagine how much he's suffering right now."
Mother asked while Kanao approached me holding Kaigaku's sword in his scabbard as she handed it to me and bowed right after before leaving.
"Don't worry,Mother.
His pain will soon be gone because he'll be the newest and refined stronger version of himself.
After all,it wouldn't hurt to have another Hashira would it?"
I asked smiling amusedly while watching the battle unfold as the mists cleared revealing Kaigaku on his hands and knees with his head down.
Then I stood up and changed into my demon slayer uniform with his sword in hand as I teleported to the platform he's standing on while I crouched in front of him with my smile not leaving my face.
"Do you know what purpose you serve for me?"
I asked watching him kneel as I placed his sword down in front of him while I stood up with a smile.
"Kill every slayer you come across and lend them my blood.
Be wary of the Hashiras and slayers that are with you.
Understand?"
I ordered as I watched him grab his sword before standing up and nodded while I snapped my fingers to teleport him somewhere else.
Then I teleported back to my estate as I sat down on the porch watching the garden while Yoriichi sat beside me.
"Tired already?"
Yoriichi asked while I nodded and leaned to his shoulder as I gently grabbed his hand.
"You have no idea.
But at least the Corps will soon become as a Demon Corps."
3rd POV
"Because the members of it are all demons now except for the Hashiras?"
Yoriichi asked glancing at the h/c haired girl who turned at him and responded with a smile as the girl chuckled while watching the blue sky.
"Are you worried?"
Y/N asked with her smile not leaving her face while Yoriichi nodded not facing the girl as he kept his face forward.
"There's nothing for you to be worried about,Yoriichi - kun.
Because even if I did get killed by the hands of the demon slayers I always come back because death is nothing but a mere word for me."
The h/c haired demoness added smiling profusely as the red haired man glanced at her while watching her beauty shine brightly.
"Then let me bid you goodbye for our long mission."
Yoriichi replied facing the girl with a warn smile while Y/N gazed in his crimson red eyes she smiled at him in response.
Then Y/N's crow landed on her shoulder right after the two separated from their kiss as the h/c haired girl glanced at the bird while the demon crow's eyes glowed red.
"There's been an urgent Uppermoon meeting including the Lowermoons as Father is currently in distress due to Lower One's betrayal when he came across his slayer sister in the train causing a backfired mission for the Upper Six resulting in him failing to deliver a train filled with passengers to the rendezvous point.
So now the Lower One's position is empty with the former holder of it now a traitor as he's aiding the Corps to our defeat and Father luckily erased the important ones in his memories which means the plan continues under a different circumstances."
Kiriya's voice answered through the crow as its eyes returned back to normal and flew away while the h/c haired girl had an empty expression.
"Just as I thought.
All this time when he's under my Father's complete control his consciousness was fighting back which means it won't be long once he started his slayer training and that will give him a boost to mastering the Sun Breathing while in demon form."
Y/N stated while standing up with Yoriichi doing the same and they instantly disappeared within seconds as they arrived at the Infinity Castle with Nichika and Hinaki standing side by side.
Then the h/c haired girl jumped down behind the two as she stood up straight with a blank expression while she took a step forward watching the Twelve Kizukis standing on different platforms with the upper ranks all sitting down in a kneeled position and the lower ranks standing idly.
"I'm sure you're all curious to hear why there's a sudden meeting regarding about the Twelve Kizukis.
Well,allow me to put an ease to those brewing questions and confusions for you.
Lower One has betrayed us and with our Master,my Father going in a distressed rampage leaving Mother to take care of him at the moment...that leaves me being your current leader.
Which means I get to do what I please with all of you as unlike Father I treat those below me with strictness and failure is something I don't tolerate even if you have a valid reason why.
Now then,shall we start on what I'll be doing to each of you if you fail?"
Y/N asked sitting down on throne made out of shadows with a devious smile painting her face while leaning on her side resting her head on her fist as she crossed her legs and her eyes filled with a sadistic gaze.
And the all the Lowermoons started giving a nervous look as sweatpores appeared on their foreheads and cheeks while a heavy atmosphere weighed down on the entire castle.
As for the Uppermoons they all bowed their heads in submission with solemn while they remained quiet.
"Every single one of you...are so pathetic to look at.
I'll start with the Lowermoons,you're all weak that everytime you encounter a slayer it'd take you at least an hour to get defeated and even your blood demon arts needed a complete refinition.
As for the Uppermoons you're all too spoiled to say that just because you hold that rank doesn't mean you get to do what you want.
So this is what I'll be demonstrating in front of you to give you a clear reason to fear which will force you to forget the fear you hold from the Corps and our Master."
The h/c haired demoness added snapping her fingers as a teenage boy appeared from the shadows while everyone present watched the male quiver and shake in fear.
Then the boy's body started bending in different ways as the cracks of a broken bone ringed through everyone's ear while they watched the boy get brutally murdered right in front of them with everyone showing complete signs of shock and fear.
"That's how I preferred to kill a human before eating them.
But do you want to know what would happen if I played this kind of term to a demon?While sunlight is their only weakness that means I can play with them until a grow tired.
And yet that will never satisfy my sadism so what do I do instead?Experiment on them and turn them into my demon army that has nothing but a need to kill and destroy."
The Upper Zero expressed as the corpse that laid on his pool of blood started twitching and shaking slowly transforming while the two elder twins was unfazed by the pure sadism their adopted sister were showing.
Then the dead boy sooned turned into a demon - like beast as it growled with its teeth drooling while it walked behind the trio like a tiger ready to pounce on its prey once something happens to the h/c haired demoness and the twins.
"So then,here's what we'll be playing."
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Demon Slayer Headcanon
* During Kaigaku's struggle to try and escape from the Uppermoons Y/N injected her blood in him using a mosquito
* Kaigaku never turned into a demon,he's just under Y/N's control with little amounts of her blood circulating inside him which means she can make her blood invade his entire veins when she wants to
* Yoriichi wasn't worried at Y/N when he asked her,he's only going to miss her because of the mission that she won't be making any long or sudden visit at the Infinity Castle
* The Mugen Train Arc still hasn't started yet so the information Kiriya gave to Y/N is where Kyojuro were placing some demons on the stations to pick up the passengers that overfilled the train
* Tanjiro was always conscious the entire time but because he knew that if he ever tries to do anything that might arouse a suspicion to Kagaya and the Uppermoons including Y/N he had to break off the control Kagaya has by surrendering the last of his humanity causing him to survive and escape the Demon King's control but in exchange of losing the important memories he had during the Lowermoon meeting