December.
The final month of the year.
During this time, schools everywhere were on winter break, granting students a long vacation and the chance to return home for the holidays.
After all, with New Year's just around the corner, many were eager to reunite with family—no matter how cold the winter weather might be.
Unfortunately, this seasonal rhythm didn't quite apply to Itogami Island.
As an artificial tropical island floating in the Pacific, even in the depths of winter, temperatures rarely dipped below 20°C. The sun blazed as fiercely as ever, casting deep shadows beneath the lush, verdant trees lining the streets. "Cold" was hardly the word to describe it.
Still, Itogami Island did observe winter break.
Two months had passed since the festival, and now, as schools closed, many residents prepared to leave the island.
But as a Demon Sanctuary, entering and exiting Itogami required cumbersome procedures—not to mention expensive plane tickets. Those returning home had to book early, resulting in a bustling atmosphere that almost rivaled the festival itself.
At least, that was the case for those who had left during the festival and were only now returning.
No amount of self-reassurance could change the fact that two whole months had passed—a reality that carried undeniable consequences.
Especially for Rozen.
And so, in the high-end residential district of Itogami Island's West District, the door to a luxurious penthouse apartment quietly creaked open.
"I-I'm… home…?"
A timid voice preceded the cautious peek of a head through the doorway.
The owner of said head wore the expression of someone tiptoeing through a minefield, his voice barely louder than a mosquito's whine.
"Natsuki-nee…? Are you home?"
The speaker, of course, was Rozen, who had just returned to this world after his long absence.
After scanning the apartment and confirming its emptiness, he let out a deep sigh of relief.
"Phew… She's not here."
He slipped inside like a fugitive dodging the gallows, hastily shutting the door behind him and wiping imaginary sweat from his brow.
His Servants, watching from within his blood, could only stare in bewilderment.
"S-Senpai…? What are you doing?"
Mash sounded utterly lost.
Rozen scratched his nose awkwardly.
"Is this 'Natsuki' really that terrifying?"
Jeanne [Alter], ever perceptive, cut straight to the heart of the matter.
"I've never seen you this nervous before. She must be something else."
Artoria [Alter] crossed her arms, intrigued.
"Is she a powerful enemy, Rozen-sama?"
Serenity, ever earnest, readied herself for battle.
Rozen sighed dramatically.
"You don't understand. She's not just a 'powerful enemy'—she's a terrifying one."
As if to emphasize his point, he shuddered and hugged himself, recalling some unspeakable horror.
The truth was, Rozen had left this world abruptly—guided by Miracle to another world where he could unlock its true power.
He hadn't been able to say goodbye to anyone.
And now, after vanishing for two whole months without a word…
"Just imagining how furious Natsuki-nee must be… It's terrifying."
Rozen's cowardice was absolute.
Hearing this, his Servants began conjuring their own mental images of this so-called "terrifying enemy."
Mash pictured a proud, short-tempered woman like Olga Marie.
Artoria [Alter] envisioned a monstrous, tentacled abomination.
Jeanne [Alter] imagined a fire-breathing saint.
Serenity shuddered at the thought of a slimy, untouchable figure.
Each of them braced themselves for the worst.
And then—
"Oh? So you do know how to be afraid?"
A voice—small, crisp, and dripping with icy authority—cut through the air.
Rozen froze.
His Servants tensed, instantly on high alert.
Only Rozen, pale as a ghost, seemed unwilling to accept reality.
(Why is she here?!)
He screamed internally.
He had checked with Wise Eye before entering—no one was home! He had even hesitated at the door like a coward! How was this possible?!
…Of course, deep down, he knew.
This was a Witch's domain, layered with barriers and surveillance. Add Space Manipulation Magic to the mix, and she could return at any moment with a mere thought.
There had never been any hope of sneaking in unnoticed.
Unless, of course, he had chosen never to return at all.
And so—
"Bzzzt!"
A spatial distortion rippled through the air.
A girl appeared—petite as a doll, with delicate features and an air of regal elegance. She wore a black gothic lolita dress and held a lace fan in one hand.
Her icy gaze locked onto Rozen like a predator sighting prey.
"N-Natsuki-nee…"
Rozen's smile was the very picture of forced cheer.
This was Minamiya Natsuki—his older sister in this world.
"So. You finally decided to come back, huh?"
Her voice was sweet, but her teeth were gritted.
Meanwhile, Rozen's Servants stared at the tiny, doll-like girl before them.
"...This is the 'terrifying enemy'?"
Their mental images shattered like glass.
A herd of imaginary alpacas stampeded through their minds.