My demon slayer au (kokuzan or maybe all x muzan)

The infinite castle

-you all are idiots!? You can't even find that bluespider lily!?

Kokushibo shouted with annoyence.

-w-were sorry master...

Then kokushibo slided the demons head.

Kokushibo: Did i told you to speak!?, Nakime!? Teleport them out the meeting is over!?

Nakime quickly nodded and struck the biwa and the demons were teleported to their places.

Kokushibo: Hey woman! Teleport me to my room now and also teleport muzan after me.

Nakime: o-okay m-master

_______________________________________

Kokushibo was now in his room sitting in his chair and Muzan then teleported infront of kokushibo. Muzan then bowed.

Muzan: you need me master?

Kokushibo: yeah, i am very stress from shouting at those stupid demons that can't find that stupid blue spider lily. And now i need you to releaf my stress....

Kokushibo said with a smirked that shivered down muzans spine.

Muzan: w-well then what you want me to do m-master

Muzan said with nervious

Kokushibo: i want you to obey me and don't resisted.... Also be a good boy and lay on the bed next to me...

Kokushibo said with a desire...

Muzan obeyed not wanting kokushibo to be mad and climbed on the bed and lay there...

_______________________________________

Meanwhile outside

Nakime hears moans and clapping sound which became louder by minuties.

Nakime: Seems kokushibo sama is fucking muzan again.... He leterally fuck muzan yesterday.... And now again...but can't really blame kokushibo sama caused muzan has a beautiful and sexy body.

_______________________________________
End sorry guys..

How kokushibo is a demon king
Well when kokushibo was a human named michikatsu he was jealous of yoriichi who was blessed by gods. Yoriichi have a birthmark which made hi strong and can live longer. while michikatsu unlocked his demon slayer mark but as he was not blessed by gods like yoriichi will die at 25....

Michikatsu scared of dying met a doctor that made him the demon king.

Now how kokushibo met muzan.

Muzan was born weak and his sickness can't be cured but have a husband and child. At night when they were sleeping someone knocked on the door muzan woked up and open the door. Kokushibo appeared and offered muzan that he can cure his illness and muzan accept it not knowing he will become a demon.

Kokushibo turned muzan into a demon because he find muzan very beautiful as muzan has red eyes and black culy hair and pale skin.
Kokushibo was jealous of muzans husband and when he turned muzan into a demon muzan losed control and ordered muzan to kill his husband and child....

Thats all😋