I was supposed to be heading East.
Instead, I had been walking alongside a set of iron railroad tracks through a freezing mountain pass for two days, entirely because my Kasugai crow had given up on giving me verbal directions and resorted to just angrily pecking the back of my head whenever I turned the wrong way.
The night air was bitterly cold, biting through the thin fabric of my purple Slayer uniform.
I was chewing on a piece of dried, heavily salted venison, my left hand resting casually on the moss-green hilt of my katana.
I paused, stopping dead in the center of the tracks.
I didn’t hear it first; I felt it.
A deep, rhythmic vibration trembling through the iron rails beneath my boots.
It was a train.
But layered beneath the mechanical chugging of a steam engine was a sickening, heavy aura that made the hair on my arms stand up.
It smelled like a slaughterhouse left out in the sun.
I stepped off the tracks, climbing a steep, rocky embankment overlooking the curve of the mountain pass.
I found a comfortable boulder, sat down, and waited.
Five minutes later, the Mugen Train roared around the bend.
It was a grotesque nightmare of modern engineering and demonic biology.
The exterior of the train cars was pulsing with thick, bruised-looking meat.
Massive, bulbous eyes blinked from the roof, and thick tentacles whipped wildly in the wind.
I unholstered my double-barreled Nichirin shotgun, checking the chambers.
A demon the size of a locomotive was a buffet.
If I could tear a chunk off that thing and activate the Devourer’s Physique, the stat multiplier would be astronomical.
I stood up, preparing to slide down the embankment and intercept the engine.
The air in front of my face violently glitched.
[CRITICAL WARNING: The Will of the World strictly prohibits your interference in this narrative checkpoint.] [Target: Lower Moon 1 (Enmu) is a mandatory growth milestone for the Protagonist (Tanjiro Kamado).
Engaging the primary target will result in a Tier-1 Purge.] [Current Objective: Standby.
Do not alter the script.] I stared at the blinking yellow text, feeling a familiar, burning spike of pure spite.
“You’ve got to be kidding me,” I grumbled, lowering the shotgun.
“It’s a giant meat-train.
There’s enough to share.” [The Will of the World does not share.
Sit down, Host.] The screen vanished.
I gritted my teeth, sliding the shotgun back into its holster.
I sat back down on the boulder, crossing my arms over my chest.
I was a swordsman, not an audience member, but a deal was a deal.
If the universe wanted me to play the role of the absentee brother for this fight, I would sit on the bench.
But I didn’t have to look away.
From my high vantage point on the ridge, the battle playing out across the speeding train was a spectacular, violent light show.
Through the shattered windows of the rear cars, a blinding flash of golden light strobed repeatedly.
The air cracked with the sharp, ozone-rich smell of an approaching storm, followed by the deafening boom of thunder.
Zenitsu.
The chronically terrified kid was apparently ricocheting through the narrow aisles like a localized lightning bolt, severing tentacles faster than the demon could regenerate them.
Near the front, the feral boar-kid, Inosuke, was tearing into the roof of the engine, his dual-wielded jagged blades ripping through the thick walls of meat with chaotic, animalistic fury.
But the true spectacle was happening on the middle cars.
Even without the magical, elemental visuals of Breathing Styles that the others presumably saw, the raw physics of the fight were awe-inspiring.
Kyojuro Rengoku, the Flame Hashira, was defending five passenger cars simultaneously.
He didn’t just cut the demon’s flesh; he obliterated it.
He moved with a speed and ferocity that ignited the air around him through sheer kinetic friction.
His footwork was flawless, planting with such crushing force that the reinforced steel roof of the train buckled beneath his boots.
He was a hurricane of steel and overwhelming physical torque.
I watched him, leaning forward on my knees, a genuine smirk crossing my face.
That, I thought, is a real swordsman.
No gimmicks.
No shortcuts.
Just absolute, devastating mastery of the blade and the body.
Rengoku was a monster.
If he had been born in the East Blue, he would have been a Warlord within a year.
Watching his flawless technique made the sting of the System’s leash a little more bearable.
Up near the engine, the true climax was unfolding.
Tanjiro was battered, bleeding, and desperately trying to reach the demon’s central core—the neck bone fused with the boiler of the train.
The roof near the front was completely torn open, exposing a nightmare of thick, armored bone and thousands of blinking, hypnotic eyes.
Even from a mile up the ridge, I could feel the sudden, intense spike of heat radiating from the protagonist’s blade.
Tanjiro’s aura completely shifted.
It wasn’t the fluid, adaptable rhythm of Water Breathing anymore.
It was deeper.
Heavier.
He launched himself into the air, perfectly synchronizing his strike with Inosuke’s brutal assault that shattered the demon’s bone-plated defenses.
Tanjiro gripped his black sword with both hands, the muscles in his arms bulging as he took a ragged, desperate breath, and brought the blade down in a flawless, devastating vertical arc.
The black blade sheared through the massive, reinforced neck bone of the train.
A deafening, inhuman shriek ripped through the valley.
The sound wasn’t just loud; it was a physical shockwave of agonizing despair.
The grotesque meat lining the train cars instantly began to rot and bubble, turning a sickly shade of grey.
But killing a demon the size of a locomotive comes with a massive, undeniable problem: physics.
The moment the neck was severed, the demonic flesh that had hijacked the train’s mechanical joints rapidly deteriorated.
The Mugen Train was traveling at full speed down a winding mountain pass.
Without the demon holding it together, the structural integrity of the train completely failed.
The engine jumped the tracks.
The screech of tearing metal was deafening, drowning out the demon’s final death rattle.
The front cars slammed into the dirt, violently jackknifing.
Momentum carried the rear cars forward, launching them into the air like discarded toys.
Wood splintered, steel warped, and the entire valley filled with a massive, choking cloud of dust and steam.
The train cars crashed into the earth, rolling over and over until they finally came to a grinding, catastrophic halt.
“Well,” I muttered, standing up from my boulder and stretching my legs.
“That looks expensive.” I began my descent down the rocky embankment.
Because of Genya’s fragile frame, I couldn’t just jump the hundred-foot drop like I would have in my old body.
I had to actually climb down, navigating the jagged rocks and loose scree.
It took me a few minutes to reach the valley floor.
By the time I walked through the settling dust, the crash site was eerily quiet.
Train cars lay scattered across the valley, twisted and broken.
Yet, remarkably, I didn’t smell a single drop of fresh human blood.
Rengoku and the others had somehow managed to use their techniques to cushion the impact for the two hundred passengers.
It was an absurd, superhuman feat of crowd control.
I navigated through the wreckage, the crunch of my boots echoing in the quiet night, keeping to the shadows.
I found Tanjiro lying on his back near the ruined, steaming engine.
He was clutching his stomach, bleeding heavily from a stab wound, his chest heaving with exhaustion.
Rengoku stood over him, entirely untouched by the crash, his bright yellow and red hair blowing in the cold wind.
“Focus your breathing, Kamado!” Rengoku instructed, his voice booming with unshakeable optimism, entirely unfazed by the derailed train behind him.
“Find the torn blood vessel and stop the bleeding!
Total Concentration Breathing can mend the flesh!” I leaned against a piece of twisted scrap metal in the shadows, crossing my arms.
He needs a doctor, not a breathing lesson, I thought, rolling my eyes.
I was just about to step out of the shadows, reveal myself, and see if there was any viable Lower Moon meat left in the wreckage to scavenge for later, when the air in the valley died.
It wasn’t a gradual shift.
The temperature plummeted instantly, turning my breath to white mist.
The lingering smell of Enmu’s rotting flesh was completely erased, replaced by an overwhelming, suffocating pressure that made my Iron Stomach physically clench.
This wasn’t Gokaku.
This wasn’t the arrogant swamp lord in Kaza town.
This was the sheer, crushing gravity of an apex predator.
The remaining dust over the crash site suddenly parted, blown away by a violent shockwave of displaced air.
A loud, heavy THUD echoed through the clearing as a figure landed in the dirt a few dozen yards away from Tanjiro and Rengoku.
He didn’t look like a grotesque monster.
He looked like a martial artist.
He had short, spiky pink hair, pale skin covered in intricate, dark blue tattoos, and wore a simple, open vest.
His eyes were a terrifying, glowing yellow.
Etched directly into his irises was the kanji for ‘Upper Rank’ and ‘Three’.
Akaza.
He slowly stood up from his crouch, cracking his knuckles.
He didn’t look at the derailed train.
He didn’t look at the bleeding boy on the ground.
His burning, yellow eyes locked instantly onto Rengoku.
“What a magnificent fighting spirit,” Akaza smiled, revealing sharp, predatory teeth.
His voice was calm, conversational, but laced with an absolute, terrifying confidence.
“You have honed your body to the absolute peak of human potential.” Rengoku’s smile vanished.
His hand dropped to the hilt of his sword, his jovial aura instantly replaced by a razor-sharp killing intent.
“I am the Flame Hashira, Kyojuro Rengoku,” he stated, his voice devoid of its usual booming cheer.
“I am Akaza,” the demon replied, holding out a hand.
“Let me give you a wonderful proposal, Kyojuro.
Become a demon.” I stayed perfectly still in the shadows.
The System hadn’t issued a warning.
The Will of the World was silent.
That meant the script didn’t care what I did here.
I slowly, silently unholstered the double-barreled Sun-Spitter with my right hand.
I drew the moss-green katana with my left.
“No thank you,” Rengoku said firmly, drawing his blade.
The steel glowed with a vibrant, fiery red.
“I will never become a demon.
We have differing values on what is beautiful.
I will fulfill my duty, and I will not let anyone here die!” Akaza sighed, a look of genuine disappointment crossing his face.
“I see.
If you won’t become a demon…
then I will just have to kill you.” The Upper Moon dropped into a terrifyingly low martial arts stance.
The air beneath his feet warped, a glowing blue compass needle manifesting on the ground around him.
Technique Deployment: Destructive Death Compass Needle.
He exploded forward.
The ground shattered where he stood, his fist pulled back to deliver a strike that would punch a hole straight through Rengoku’s chest before the Hashira even had time to raise his guard.
My combat instincts, forged over thousands of battles in another life, screamed in perfect clarity.
I didn’t hesitate.
I stepped out of the shadows.