Japan – Fuyuki, Singularity F.
Particles of blue spiritrons slowly converged, twisting and coiling in the air before taking human shape. The light faded, revealing Kagami's figure—his pale blond hair swaying faintly in the wind, the strands near his temples shimmering with a faint azure glow like cracks splitting the darkness. His eyelids lifted, unveiling a cold gaze that reflected the world before him.
In his sight stretched a ruined city: buildings fractured as though on the verge of collapse, black smoke billowing into the skies, molten magma flooding across the ground like the veins of some colossal beast. Scorching heat lashed his skin, stinging as if under torture.
"…Hmm~" Kagami's lips curled into a half-smile, steeped in scorn.
"So this is what they call a Singularity? Hmph… interesting."
He stepped forward. Each time his boots struck the scorched earth, they hissed sizzle like fat spattering on a pan. The leather cracked under the heat, the soles softening until chunks began to melt away. Kagami lifted his foot, grimaced, and saw the sole eaten through.
"Goddammit!!" he spat, face contorting.
"This is no different than walking barefoot on a frying pan!"
Grinding his teeth, he pressed on, ignoring the acrid stench of burning leather and the wisps of smoke trailing from what was left of his boots.
…Result: -1 pair of boots.
His pace slowed as his eyes swept across the landscape. The path was pitted with craters and jagged scars, the ground etched with the remnants of battle: gouges carved by blades, broken arrows jutting from the soil, the faint glow of magic rune long since faded. Though time had dulled them, there was no mistaking it—this place had borne witness to a desperate clash.
"Looks like someone once fought for their life here…" Kagami brushed his fingers along a deep fissure carved into stone, as if feeling the ghost of the blade that had struck.
"Heroic Spirits, huh? If I recall… they're heroes enshrined in history, their souls preserved within the Throne of Heroes. Through the Holy Grail ritual, they can be summoned as Servants… Hmph, that's pretty interesting."
Just as Kagami bent down to examine the scars on the stone, he suddenly froze. His hand fell loosely at his side, and in the span of a single breath—the world around him shuddered.
The ruined city blurred and dissolved, replaced by an endless white void. Before him stretched rows upon rows of colossal bookshelves, extending into infinity, stacked layer upon layer as if reaching into eternity itself.
…The Gaia Library.
A glint of seriousness flickered in Kagami's eyes as his voice dropped low:
"Alright then… let's see. Just what kind of farce went down in this Singularity."
He strode toward the nearest shelf and casually pulled out a book. Flipping through a few pages, he shook his head.
"Not relevant." Snap—the book was shut and slid back into place.
He moved a few steps further, drew another tome, scanned the glowing script that danced across the pages. After a brief silence, he returned it as well, continuing his search as if he were strolling through a secondhand bookstore rather than investigating the mysteries of the world.
On and on it went, until finally, Kagami halted at the very center of the void. Closing his eyes, he murmured as though reciting a password:
"Keyword: Singularity… Fuyuki, Japan."
Boom. The whiteness rippled like water struck by a stone. Bookshelves groaned, shifted, collided, then reformed into an unseen order. Within moments, the sea of shelves vanished, leaving only a single lone bookcase standing before him.
Kagami stepped forward and drew a volume from its spine. The instant his fingers touched the binding, streams of data surged forth, rearranging themselves into words, symbols, and hazy images that projected straight into his vision.
"hehe~…" His eyes narrowed, lips curling upward.
"So I'm finally about to find out what turned Fuyuki into this mess."
—Year 2004. The Fifth Holy Grail War began… at first, everything was normal. But then it twisted.
In a single night, the town was engulfed in flames. Humanity was wiped out, leaving only Servants rampaging in endless slaughter.
During that war, Saber was the first to restart the Grail after all the Masters vanished. Worse, she fought with escalating frenzy, growing stronger the madder he became—like a fish thrown back into water.
One by one, that Saber defeated Archer, Lancer, Rider, Berserker, and even Assassin.
And yet, those defeated Servants did not disappear. They were twisted into black husks, bound to a single command: hunt down and kill any survivors.
At present, only Caster still retained his sanity.
Reading this, Kagami gave a small nod, shut the book, and slid it back where it belonged. The whiteness collapsed, and he slipped out of the Gaia Library, returning to the burning ruins of reality.
"So this so-called Holy Grail War is nothing but bad news… Saber, huh? If I remember right, that class is just the sword-wielding type, isn't it." He scratched his head, muttering under his breath.
Just as Kagami pressed onward, the sharp clack-clack of bone echoed all around him. He lifted his gaze—skeletal soldiers had encircled him, their gaunt frames rattling, empty sockets glowing with eerie light. Their hollow stares locked onto him like predators sizing up prey.
"Well, well… a pack of disposable grunts, huh? This might be fun." Kagami rolled his shoulders, loosening up, lips curling into a grin.
"Alright then! Think of it as an appetizer before I take on the Heroic Spirits themselves!"
Before he even finished his warm-up, one skeleton lunged forward, rusty blade swinging straight for his skull.
Kagami smirked, lowering his stance. In a fluid motion, he leaned back almost to the ground, then snapped his leg upward like a steel whip. CRUNCH! The kick shattered the skull to fragments, bone shards scattering as the body crumpled into a heap.
"Couldn't even handle one warm-up kick? Pathetic. Even Dai-Shocker's cannon fodder put up more of a fight." He scoffed, laughter sharp with contempt.
Reaching behind him, Kagami drew forth the Lost Driver from the void, strapping it to his waist in one decisive motion. Clack! The buckle locked in place, a faint azure glow flashing across its edges.
From his coat pocket, he produced a gleaming USB-shaped device—its silver-white body etched with a bold golden E. Without hesitation, he pressed the button.
[Eternal!]
The electronic call rang out, merging with the crackle of fire that filled the hellish landscape. Kagami smirked, twirling the Memory between his fingers.
"Well then… let's get the show started."
He slammed the Eternal Memory into the Driver's slot. The heavy standby hum erupted, pulsing like a chaotic jungle beat reverberating through the scorched air.
One sharp flick—
"Henshin!"
[Eternal!]
In that instant, a storm of wind and lightning exploded outward. Plates of silver-gray armor spiraled around him, locking together piece by piece until his entire form gleamed in radiant white. Behind him, a black cape snapped open, thrashing wildly as though to devour the fiery backdrop.
Ghostly blue flames etched themselves along his arms and legs, flickering cold and merciless. From beneath the mask, his eyes blazed with a ferocity that stripped away every trace of mockery.
—Kamen Rider Eternal.
Kagami spread his arms wide, voice rumbling low, like a verdict handed down by the underworld itself:
"Saa… jigoku o tanoshimi na."
(Now… Enjoy your hell.)
"GRAAAHH–!!"
The skeletal horde shrieked, joints rattling like war drums as they surged forward, a tidal wave of death. Spears, arrows, and rusted blades tore through the air, all aiming to rip Kagami apart.
BOOM!!
The ground shook as a burst of azure pressure exploded from Kagami, sweeping away smoke and cinders. In his grip, the Eternal Edge shimmered—a short blade, yet so sharp it seemed to slice even the light around it.
"Yoishi… let's see if you can give me a little exercise."
SWISH!
A skeleton brought its sword crashing down, but before the blade could even reach him, Eternal Edge flashed. A pale-blue arc streaked across its neck. A heartbeat later, the skull split clean in two, engulfed in azure fire before collapsing into ash.
"Empty. As expected." Kagami sneered.
The rest charged in like starving wolves. Kagami spun, his dagger tracing blue trails through the air. Every slash, every thrust landed with surgical precision—bones shattered, hollow sockets erupted in ghostly flames.
A spear lunged from his flank. Kagami tilted his body aside, Eternal Edge slicing clean through the skeleton's chest. SCHLIK! The blue flames spread like venom, consuming the bones in an instant before detonating into dust.
From afar, an archer loosed an arrow straight for his head. Kagami didn't even bother dodging—he flicked his wrist, Eternal Edge knocking it aside. The arrow burst apart like paper scraps.
"Pointless. To me, you're nothing but dry kindling waiting to be lit."
With that, Kagami raised his dagger high. Blue fire surged from his hand, coiling around the blade before he spun in a sweeping arc. His black cape unfurled like the scythe of death itself.
KRA-KOOM!!
A roaring wave of azure flames tore outward. Dozens of skeletons ignited at once, shrieking as they collapsed into heaps of burning ash. For a moment, it was as though hell itself had erupted in the ruins of Fuyuki.
At the center of that inferno stood Kagami. Eternal Edge lowered, its blade still glowing faintly before the fire finally died down. The golden Visors of his helmet reflected the blaze—like the eyes of a beast, merciless and unyielding.
He turned slightly, each step echoing through the field of cinders, his voice dripping with disdain:
"Hmph… ridiculous. Why would I ever expect trash like this to bring me even a shred of entertainment?"
He walked on, his black cloak fluttering amidst the fading azure flames. It was then Kagami heard it—hurried footsteps echoing closer. He stopped, tilting his head. From the swirling smoke, two familiar silhouettes emerged—Ritsuka and Mash.
"Ritsuka… Mash?"
Ritsuka rushed forward, but the moment her eyes took in the scene—the cratered ground, the scarred earth gouged with blade marks, the countless skeleton corpses still burning in blue fire—she froze in her tracks.
At the center of that inferno stood a lone white figure. The golden eyes of his helmet bore down on her with a chilling gaze. The cold weight of it sent shivers down her spine, her heartbeat stumbling in panic.
"Mashu… is… is that a Servant?" Ritsuka's voice trembled.
Mash instantly felt the oppressive killing intent crushing down on them. Instinct as a warrior screamed. She stepped forward, shield raised firmly, planting herself in front of Ritsuka. Her eyes narrowed, tense as if facing a calamity.
"Stay behind me, Senpai! That thing… is far too dangerous."
Kagami chuckled at the sight, turning fully toward the two girls. He raised his hands lightly, a mock surrender, his tone laced with playful teasing:
"Why so tense, Mash? …And you too, Ritsuka. Well~, I'm glad to see you both safe."
Both girls jolted at once. That voice—there was no mistaking it.
"K–Kagami-san?!" Mash slowly lowered her shield, eyes wide with disbelief.
"Eh?! Impossible…! That terrifying aura… belongs to Kagami?!" Ritsuka gasped in horror.
Kagami smirked but said nothing. Slowly, he reached for the Eternal Memory slotted into the Lost Driver.
Clack.
Instantly, a storm of wind exploded outward. The white armor cracked apart into fragments of gray, scattering into the void. The black cloak billowed one last time before dissolving into nothingness—leaving only the familiar figure of Kagami, standing calmly amid the ashes.
He raised his hand, giving a casual little wave, his smile almost sheepish.
"Yo… Ritsuka, Mash."
In that instant, the suffocating tension shattered.
"It really… really is Kagami-san!!" Mash cried out, her eyes sparkling with relief and joy.
---
"I never thought Kagami-san could be that terrifying… I nearly had a heart attack right there." Ritsuka clutched her chest, still pale as she muttered in disbelief.
Kagami burst out laughing, waving his hand dismissively:
"Hahahaha! Well, that… I probably just spooked you a little. Anyway~, while we're at it… Mash, what's with that getup of yours? Half-knight, half-mage cosplay or something?"
At that, Mash, walking beside him, faltered slightly before giving an awkward smile. Her hand brushed against the massive shield she carried.
"Ah… this? This isn't cosplay, Kagami-san. This is the Mystic Code of the Heroic Spirit I've fused with. I'm what you'd call a Demi-Servant now."
"Demi… what now?" Kagami arched a brow, face twisted like he'd just heard the name of some shady employment contract.
Seeing his doubt, Mash straightened her posture, doing her best to explain clearly:
"I don't know everything… but a Demi-Servant is a living human who has incorporated the Saint Graph of a Heroic Spirit into their own body, allowing them to use the Heroic Spirit's abilities as if they were their own... just like me now."
Kagami crossed his arms, nodding in a way that looked suspiciously "dangerous."
"Umu… umu… I see, I see."
He nodded seriously a few more times, then suddenly declared, sharp and absolute:
"So in short… it's basically the same as that guy Kouta Transform into Kamen Rider Ghost's—using a living body to borrow the powers and memories of the dead. Right?!"
Ritsuka instantly facepalmed, while Mash just stood there with a silent "…" expression. Her entire earnest explanation had been reduced, in the blink of an eye, to Kagami's "neighborhood analogy."
"…Anyway, even if I don't really get it—Kagami-san, what about you? What was that form from before?" Ritsuka quickly cut in, breaking the awkward mood, curiosity flashing in her eyes.
"Ah, that armor? That's simple." Kagami planted a hand on his hip, speaking as though he were unveiling a brand-new product:
"I'm a Kamen Rider… name's Kamen Rider Eternal."
"Kamen… Rider?" Ritsuka tilted her head, utterly confused.
Kagami flicked his hand dismissively, his voice dropping into a serious tone as he built up an image of grandeur:
"The so-called Kamen Rider… is one who hides their true heart and emotions behind a mask, dons armor like mine… and fights for the sake of others."
"Waaah! So Kagami, you're actually a superhero!" Ritsuka's eyes lit up instantly, like a fangirl spotting her Marvel idol.
"No." Kagami cut her off flatly. A flicker of something complicated passed through his eyes as he spoke slowly:
"I'm no superhero… I'm a butcher."
Ritsuka froze, confused.
"Eh? Then… why would you say that?"
Kagami smirked, his laugh carrying a note of self-mockery.
"Hahaha… that's a long story. If I told you, you'd probably hold a vote to kick me out on the spot. Anyway, forget it! I've already paid the price for the things I did. What's more important now is… do I get hazard pay for fighting off monster swarms, or not?"
Mash: "…"
Ritsuka: "…"
The tragic atmosphere he'd built up collapsed instantly into a cheap workplace comedy skit.
Before either of them could respond, a sudden scream of terror tore through the air from somewhere in the distance. Mash, Ritsuka, and Kagami immediately dashed forward, sprinting over rubble toward the source of the cry for help.
---
On the far side of the ruined city, a familiar white-haired woman was frantically running for her life. In her panic, Olga stumbled on the cracked ground, her trembling hands raising to fire bursts of crimson magic bullets. The glowing projectiles tore through several skeletons that lunged at her.
"Damn it… damn it all!" she grit her teeth, unleashing another volley.
But in a single moment of vulnerability, a skeleton dropped from a broken lamppost above, rusty sword slashing straight down at her. She tried to retaliate, but the skeletal warrior slipped past her shots with ease. Death loomed right before her eyes. All she could do was shield her head, squeeze her eyes shut, and scream in despair:
"Save me, Lev!!"
CLANG!!
The shriek of metal on metal rang out. Olga opened her eyes in a tremble—only to see not a blade, but a sturdy round shield glowing with blue light standing between her and certain death.
"…Mash?" she whispered, hardly able to believe it.
Before Olga could say more, a lazy, mocking male voice cut in:
"Lev not here. But would a freshly recruited trainee Master do the job?"
"You're… Kagami?" Olga blurted, still in disbelief.
Kagami emerged from the smoke, one hand raised in a casual wave, lips curling into a smirk.
"Yo! Bossu, watching you panic and run like that… I gotta say, it's pretty damn entertaining."
A vein throbbed on Olga Marie's forehead as she roared:
"Shut up, you fool!!"
Kagami just shrugged, scratching his head as if it were no big deal.
"Alright, alright… save the arguing for later. Let's clean up this trash first, then you and I can talk about fair wages and benefits, Bossu."