Prologue: One Flame Dies, One Flame Sparks

My name is… not important.

I was someone who had lost everything. Just another person who had the misfortune of being born under an unlucky star. Just another orphan born from the tragedy of demons preying on men. Just another ember of anger that gathered around the bonfire of revenge called the Demon Slayers Corps.

In that band of demon slayers, I realized how little difference my story made in the grand tapestry of history. So, I won't burden you with details you can hear from every other Demon Slayer out there. I'll just keep it short.

My family was slaughtered by a demon. I was the sole surviving member of my clan. I was consumed with hatred and joined the Demon Slayer Corps. I staked everything I had to master just five forms of the Breath of Flames. And after an arduous year of hard work, I was finally accepted by the Flame Hashira as his Tsuguko.

But none of that matters.

None of that really matters. No, not when I'm just about to die.

"W-what are you–"

My words are cut off when my throat is slit. Blood erupts out of my neck like a geyser. My visions shakes vigorously. Everything is dyed in a grim red.

The demon before me is unlike any other I've faced before. His very presence radiates power of an unfathomable magnitude. My skin crawls reflexively. One look at him was all it took for me to realize the bitter truth.

I had met my end.

There was not a single chance of me walking away out of this demon encounter alive. This would be my last night slaying demons. My dream of avenging my late family was over.

But even still, I refused to go down quietly. If I was going to die, I'd go die fighting. I wanted an honorable death at least, like all the other fallen Demon Slayers who came before me.

"Gr-grh!" I can't even scream anymore with my vocal cords cut. Instead, a feeble gurgle of blood leaks down my neck.

I falter, almost blacking out from the sheer pain. I grit my teeth and suck in my breath. I breathe with everything I had left. Focus.

Flame Breathing. The Breathing Style I devoted an entire year of my life to learn. It was the most difficult of the five basic breath styles, said to be closest one to the original Sun Breathing.

An ordinary man would have collapsed from shock after having their throat slit. But I desperately clung on to life. Sweat beading down my pale face, I take another deep breath. One. Two. Then another.

"Oh? You're still standing," the demon says to me, mildly impressed. He stands motionlessly two sword lengths away from me. His dull uncaring eyes regarded me as if I were the lowliest of bugs.

He's dressed like a noble, wearing finely embroidered black robes. But his deathly pallor and blood red eyes gave away his true nature as a demon.

I breathe harder, gathering what little energy I have left to burn into my mind the image of the demon who would kill me.

His hair is black, long but kept tied in a knot. The ends of his bangs are curled like noodles. The tips of his fingers drip red, stained with the blood of my demon slayer platoonmates. His hands are pretty like a woman's, but they're strong enough to rip the hearts out of ten demon slayers in a minute.

Such an absurdly strong demon wasn't included in the mission briefing given by the crows.

It was only supposed to be a normal, mid-average rank mission. Gather and coordinate with a team of at least twenty-four demon slayers and stake out the mountain side of the Mt. Enzo.

Reports from the citizens spoke of a group of at least twelve low-level demons collaborating in the forest to terrorize the local villages. The higher ups had seen it fit to dispatch a group of twelve veteran slayers and twelve new recruits.

I was one of the veteran slayers. We were supposed to help introduce the new blood into the profession, get them used to the feel of actual combat.

It was supposed to be a straightforward mission. We had accomplished our tasks and slayed exactly twelve demons. We were just about to head back and report our success,

But at the eleventh hour, a thirteenth demon showed up. He came out of nowhere and decimated our platoon in a few minutes. There was something different about this demon. It had enough power to crush our numbers alone. I knew I had to get information about him back to headquarters. But it was impossible now.

My crow lied dead on the ground, useless. It was split in half by one casual swing of the demon's hands. Whatever information I could gleam off this demon would be lost along with my death.

I look at his eyes. There are no characters of any moon or number in his irises. So, I could rule out the demon's identity as a member of the 12 Demon Moons. But anyone this strong had to be a demon of well renown. One name came to mind and my body trembled in fear when I realized could be right.

Kibutsuji Muzan...!

Said to be the founding father of all demons. The strongest and oldest demon that lords over all others. A demon whose appearance is only described in rumors. All Hashira who've ever had the fortune or misfortune of meeting him have died.

That kind of monster is staring at me as I bleed to death. His face is cold and dispassionate, like he was merely regarding a squished ant squirming its last seconds of life. Screw him.

I take up my Nichirin blade. Breathing so hard that the veins on my face and hands throb, I take my last stance. "Grh!"

Breath of Flames. Fifth Form: Flame Tiger!

Tattered as I was, I lash out at the demon lord. I release a series of cutting motions I had drilled into my bones so hard, that even as my vision was patched with black blots, I could still pull them off. I squeeze out all the life I had left in me into this one attack. My breathing and my rage gave form to a giant tiger of flames that pounced onto Muzan.

This was the single attack I had the most confidence in. Even my master, the Flame Hashira, Rengoku-shishou had commended my grasp of it.

The flames of my attack are about to reach Muzan. But he doesn't flinch. He stands perfectly still. Just as I think my flames are about to burn his flesh, a tangle of tentacles sprout from his back and swats away my tiger of flames.

My eyes widen as my jaw lowers. The one attack I staked my life on is worth nothing to him. I collapse to my knees, desperate to keep living just for a second longer. My whole body is shaking. Sweat drenched, I lose my grip of my Nichirin Blade.

No, not yet!

I take another breath. Inhaling as much air as I could, I grasp my blade, using it as a crutch to remain upright. I couldn't move anymore so I could only remain kneeling. My hand trembles as I force it to keep grasping the blade.

"Pitiful Demon Slayer," Muzan says as he walks towards me. He looks annoyed now. He extends his hand out, leisurely reaches out to me, probably to choke the life out of me with his own hand.

"Why do you insist on struggling?" he asks with a strange sincerity, as if he could truly not understand the plight of the Demon Slayer Corps.

My blood drips down my neck, but still, I wait. I can't move a single step any more, so I wait for my death, while holding my sword. Just a little bit more. Walk a little faster you arrogant monster. Come on… Now!

Breath of Flames. Second Form: Rising Scorching Sun!

I swing my blade in an upward arc. A halo of fire trails after my sword. For a moment, the dark night sky is sliced up by brilliant fire. My swing should have cut straight through Muzan's arm, but somehow it remains intact. But the sleeve has been cut. Did his flesh just regenerate as it was being cut? That's just absurd!

Muzan doesn't look amused at the slightest. He's pissed now. Is that a bulging vein on the corner of his head I see? Ah, shit. I'm done. My vision fades to black.

I feel Muzan's icy hands grab the torn bits of flesh left of my neck. He inserts his fingers into me, digging through my raw exposed tissue.

"A wound like this should have killed you instantly. And yet, against all odds, you stubbornly persist," Muzan addresses me with something akin to pity, but it's an incredibly sickening feeling. "But for what? Was that attack supposed to do anything?"

I see my life flash before my eyes. Muzan's voice slowly fades in the background My vision collapses into black.

"Such needless struggle..." he coldly dismisses me. "But your tenacity might better serve my needs instead. I have a proposition for you. How would you like to become a demon?"

I can't speak anymore, and I can't open my eyes anymore. But I can still vaguely hear what Muzan is saying.

He's offering me another chance at life as a demon. He's telling me to abandon everything I stood for, everything I built up for the past year in the Corps.

I smile, at least I think I do, I'm too out of it to be sure. But I make sure to mouth the words, "Fuck off!" before stabbing my Nichirin Blade into what I think is Muzan's side.

The blade definitely hit something solid, but before it could really sink into his flesh, it snapped with one half of the blade stuck to Muzan's body and the other still connected to the hilt I'm holding.

A moment of utter silence passes and I hear Muzan sigh.

"Wrong answer," Muzan deadpans and squeezes my neck. I feel something trickling down my neck and entering my body. It's like I'm drinking ice cold water, except it's alive, slithering down my throat like a snake...

Wait, this feeling. It can't be!

"My blood at an adequate amount would have turned you into a demon, but at this dosage, your cells will be systematically destroyed from the inside," Muzan explains, his usual dreadful tone mixed with a hint of mirth.

"You only have yourself to blame for this. Had you chosen differently and not stubbornly followed through with your childish tantrum, you wouldn't be dying so pointlessly," he says before throwing my writhing body to the ground.

I feel my body convulse wildly. It's like a fire is eating away at me from the inside. My throat gurgles blood as I try to scream but fail. Through the sheer pain, I manage to open my eyes again. I see his cold expressionless face. Like a serene lifeless corpse watching from the heavens.

Fuck you. Fuck you, you piece of shit. Ah. I'd curse at him, but I can only glare and sputter my blood at his direction. My eyes tear up with blood, so everything looks red. My heart is palpitating like a wildfire. I try to control my arms, but they just flail about in pain. Shit. I can't stand. I can't breathe. I'm choking on this damn demon's blood.

"AGH!" My final sight of the world is that demon's frigid look of indifference as he watched my suffering.

Everything fades to black. There is no moonlit sky. There is no blood-stained demon. There is just black, inky black nothing.

Did I make a mistake somewhere down the road? Should I have just run away at the first sign of trouble? Or should I not have joined the Demon Slayer Corps at all?

No, that can't be. I didn't regret that. There's no way I could've lived a normal life after being the only survivor of my clan. To find happiness in this wretched world while the rest of my kin were buried in the ground, I could never have lived that down.

So, where did I go wrong? Why am I welling up with regret? I did everything I right! I did everything could! I strove hard. I never gave up. I moved forward every time I lost a comrade or failed to save someone. I trained diligently under Rengoku-shishou. I finally climbed up ranks and reached the fifth rank of Tsuchinoto. I did so many things right.

So, why? Why is my heart filled with regret at the prospect of my death? All men die eventually. Demon Slayers faster than normal. I know this, but still, I can't accept it.

If anyone will ever hear me, please, remember me. My name is important, to me at least. Don't forget that there was a Demon Slayer like me. Listen up, my name is–


Threat to Humanity detected.

Counter Guardian Intervention now implementingfailed.

Unable to achieve Spiritron Stability.

Servant Summoning System impossible.

Searching for viable alternatives…

Under the cover of darkness, in the forests of Mount Enzo, there lay a string of corpses. Men and women of all ages torn apart in gruesome fashion. The blood spilled all over the forest had not yet dried, but no animals dare come near, for these were the remains of a demon's attack.

Appropriate vessel candidate found.

One particular body was worse than the rest. It looked like the young boy had imploded on himself. His flesh burst open and riddled with grotesque holes. His skin blotched with purple rot.

Searching for Appropriate Servantfound. Summoning Counter Guardian…

A peculiar thing began to happen to the corpse. The flesh shivered as if stirring back to life. The fingers began to twitch and the blood pooling around it rippled. Bits of flesh thrown about gathered around the chest of the corpse, sewing itself back together. The sick purple hue bleached into stark white flesh. The body's black mop of hair lit up into bright fire red.

Augmented Spirit Origin recorded. Mental Corruption adjusting.

The clothes the boy wore were torn to shreds, leaving a tattered mess of rags. His broad chest was bare, but thankfully his crotch was still covered with ripped black trousers. The body slowly stood up, now fully animated. The boy flexed his arms, checking the feel of his new joints.

Counter Guardian EMIYA has been summoned. Class BERSERKER.

The boy opened his blood red eyes. His pupils were thin vertical slits, like those belonging to a beast or a monster. His eyes flared to life as his hazy newborn mind was consumed with one singular thought:

Mission Objective: Slay all the Demons!