Male OC X Kimetsu No Yaiba / Demon Slayer

Underneath The Underneath

Katsuki's POV

I can hear the annoying screaming from that damn new Upper Three from afar. Tch! What makes you think you're the only one who wants to see Oreki?! If not for his personal request, I would be there by his side! NOW I'M FUCKING MAD SO SHOW UP YOURSELF MUZAN JACKSON SO I CAN FUCKING KILL YOU!

[Author: Sorry children]

My nose caught a scent of blood... demon's blood to be exact. I crept to a corner and peek into a crack on the edge of the wall. This scene before me is just like the manga. Muzan Kibutsuji is in his pile of flesh lump waiting to evolve while absorbing Miss Tamayo. Oh, she's dead now. Whatever. Everything is according to plan. Sorry not sorry Yushiro, but Tamayo's sacrifice is crucial and it is part of the original plot anyway.

"The pest has finally come to face me once more," Muzan speaks up.

"Yeah, my hands are itchy to murder you."

"Your arrogance irritates me." He glared menacingly.

"Hmm? Do you think I can't manage? Ouch! I'm 'hurt'!" Muzan is now free from those disgusting lumps of flesh. "Oh, you had evolved. Now let's celebrate it with an ancient melody!" He grew 8 tentacles with sharp ends, but that's not even near enough to scare me.

"Where's that confidence earlier? All you did is a dodge. You're a worthless fool with a big mouth."

"Am I? Hmm, I see, it's no fun when there's no blood." My lips curved into a devilish grin. Ah... I just can't help it. Muzan finally notices that the ground had already covered in ice. "You don't feel pain, do you? Other than the nichirin blade, this one is 'harmless' that you even barely notice. You can't feel your legs, awesome right?" Muzan cut off his own leg and regenerate it back. He is no longer on the floor, instead, he's on the ceiling.

"That's it? I'm very disappointed. Do you think such a cheap trick will work on me? Surrender, and I will give you honor by being killed in my hands."

I snorted at the last sentence he said. "Pfffft! Hahahahahahaha!" I laughed and laugh like a maniac. "Surrender? Why? What are you? A mafia? Poor kid, and anti-social at a young age. Hahaha! Hey! Why don't we celebrate your birthday (evolution)? What? You don't know when is the right time? Then we'll celebrate it now!" The door around us opens and guess who? It's the Pillars. Shadow looming from every one of us as we look at him in hatred while I'm in amusement. "While we're at it, why don't we celebrate your FUNERAL too? The more the merrier!~" Muzan instinctively spawns more tentacles and his arms and legs have mouths with sharp teeth. "Oh, we can't have that. The room is too small and cramped. Let's head outside, shall we?" The room altered and all of us were outside.

"What?!! Nakime! What are you doing?!!" Ah, it's Yushiro's doing. Just in time.

"Breath of Water-" "Breath of Serpent-" "Breath of Love-" "Breath of Flower-" "Breath of Insect-" "Breath of Sound-" "Breath of Wind-" "Breath of Mist-" "Breath of Stone-"

Are you seeing this, Muzan? You've been dancing on a stage I prepared for you. A play where you are meeting your fateful end. Death missed you so much. It had been lingering in your soul ever since you were born. And finally, you will encounter death once more. However, this time, you two will be forever entwined.

Hmm... I'll just let them have their fun. Right now...

"Otouto!~" I threw a knife and it lopped his head off. "Ah geez! Why would you do that?" I stomped onto the head on the ground with a heavy force. "Owowowo! Waaaaa otouto! Please treat me more kindly!" His fake tears irritate me.

"You didn't die, huh? Even though that one knife is made from nichirin."

"Hmm, I wonder. Oh! Maybe it's just like Gyutaro and Daki's case! To kill me, you have to kill both of us. Can you even do it, otouto?~"