Late at night, before dawn, only faint moonlight filtered through the sky. A secluded house stood among trees in a desolate place, its fairy-tale grandeur basking in silver light.

CLACK! CLACK! CLACK...

The forest's stillness shattered with rhythmic footsteps approaching the mansion. As the sound grew clearer under cool moonlight, a slender figure emerged at the path's edge.

A girl broke through this silence. Her raven-black hair cascaded like waterfalls over her shoulders, two straight bangs framing her cheeks with striking individuality. Yet these locks were merely emerald leaves complementing crimson blossoms - the flowing tresses accentuated her rose-like beauty. Looking no older than seventeen or eighteen, she wore a black coat and hung a plaid scarf casually around her neck against the chill. A short skirt revealed pale thighs beneath black stockings, her figure exuding both youthful energy and seductive allure.

Carrying a large suitcase like an exile returning home, she smiled confidently at the mansion. Sapphires gleamed in her eyes as she stepped forward with resounding CLACKs from her boots. When silence fell again, she stood on stone steps, hand raised to knock gently.

"Yuki, I'm back."

The door opened to reveal another girl - black hair, black sweater, black skirt, black stockings, black shoes... Only her porcelain face and hands escaped the monochrome shroud. Her expressionless beauty studied the visitor with dark eyes. Though reunited after years apart, she merely said, "Ao, it's been a while."

Indeed, the long-haired girl was one of this world's few remaining magiasters - Ao Takamaki, wielder of the Fifth Magic and bearer of the title 'Human Rocket Launching System.' And her companion? The reserved yet proud witch who'd shared years with her - Yuki Hyakuya, forgotten by time.

"Still cold as ever," Ao sighed. "Even on my rare visits, you can't show a little happiness?"

"I am this way naturally." Yuki turned and walked inside without another word.

Ao followed into the house where Yuki simply sat at the chair, resuming her book with scholarly dedication that would shame ancient scholars. Used to her companion's habits, Ao brewed coffee in the kitchen then perched cross-legged on a sofa across from Yuki.

"Any interesting happenings lately?" Ao asked cheerfully, though their reunion carried none of the expected warmth.

"None." Yuki didn't look up.

"That's suspicious - you reading this late contradicts your usual routine," Ao smirked knowingly.

"A whim." The response remained characteristically brief.

"You're just as wooden as ever. After years together, can't you at least say something?"

Yuki said nothing. She knew Ao's aloofness rivaled her own - while Yuki lacked human emotion by nature, the so-called lively Ao simply concealed indifference beneath a facade of enthusiasm. Now she likely thought to vent after her world travels.

Back when Ao was just a high school girl, newly initiated into magic under Yuki's tutelage at this mansion - battling intruders daily in that bustling yet complaining way. Their worlds were fundamentally different: one like a free-spirited bird and the other a caged canary with gilded plumage; one reaching human perfection unafraid of anything while the other was bound by past sins.

Yet their connection defied logic - understanding without words, expressions or shared experiences.

"Who are those two?" Ao suddenly pointed to shelves where two girls stood reading: one in pink mage robes with purple hair like a scholar, another golden-haired with an attached puppet at her side.

"Witches." Yuki returned her gaze coldly.

"Witches? Though similar, they're fundamentally different..." Ao's brow twitched mischievously. "So you've secretly been collecting beauties all this time?"

Even Yuki's icy demeanor wavered slightly. Knowing Ao would spin wild theories otherwise, she explained: "They're spirits summoned through the Holy Grail War - Paracelsus and Alice."

"Two spirits at once? I've never heard of that." Ao was familiar with the Grail Wars.

"Perhaps because they're both witches too," Yuki offered.

"A witch summoning a witch... Indeed compatible."

Unwilling to overthink, she asked bluntly: "What now?"

"No plans. Since I don't need the Grail or enjoy fighting, if they wish to stay for research - fine. If not - I won't stop them."

"Hmph, typical of you," Ao mused then leaned forward with a sly smile. "Though... I'm getting interested."

"In what?" Yuki blinked.

"Obviously the Grail War!" Ao declared. "If there are so many spirits around, how can someone like me resist?"

"Just go alone then." Yuki dismissed it quickly - aware of her companion's repressed aggression.

But Ao plopped down beside her with a whine: "Come on! I'll make you sleepless forever if you don't!"

Yuki remained unimpressed. This was clearly not a request but another threat disguised as one.

"Remember the church?" she countered. "You're on bad terms with them."

Ao shrugged dismissively. "If they dare approach, I'll beat them senseless!"

"And what about the Magus Association? They may not control the Grail War, but they certainly monitor it. If you enter this conflict..."

"Hmph! The association has never controlled me and never will." Ao's arrogance was absolute. "Besides, if they try anything after clashing with the church... well."

Yuki sighed deeply.

"Will you agree then?"

"Must I really?"

"Yes!" Ao hugged her tightly - an action that startled both Yuki and the reading spirits nearby before quickly subsiding into a brief awkward silence.

Yet beneath this moment lay gravity. "There's something else," Yuki said seriously, "We might encounter... someone."

Ao stiffened.

"You know who I mean."

Silence fell between them as Ao realized the implications - not of strength but of blood: her older sister Aoi Takamaki.

Though Ao was acknowledged as a prodigy, Aoi had surpassed her in every way. The Takamaki inheritance originally belonged to Aoi until grandfather abandoned tradition for "special circumstances" involving Ao's singular magical circuit versus Aoi's comprehensive mastery.

This caused the tragedy: estrangement between sisters, betrayal that made blood thicker than water meaningless. Years later, with Yuki's help, Ao defeated Aoi and cursed her away from Mikado city. Now, through the Grail War, they might meet again - in battle once more.

"Are you certain?" Ao asked solemnly.

"Intuition of a witch," came the reply.

"...Likely then." Ao sighed, knowing witches' intuition was rarely wrong.

Meanwhile, Yuki felt equally burdened. Though her years with Ao were fewer than those lost to Aoi, circumstance forced her into this role as mediator between warring sisters.

"You'll still go?" she asked cautiously.

"Why not? Let the Grail War resolve everything once and for all!"

Thus at dawn, with two spirits in tow, they boarded a train bound for Fuyuki City - unaware of the man behind them on another car, rubbing his temples in exasperation. Most Masters were already located and redirected there... except Yuki, whose sudden reappearance he anticipated.

But what he hadn't expected was Ao being chosen as a container!

This defied logic! His bonds with her were minimal compared to Aoi's yet here she was selected instead. Though compatibility with the world's heart was good... Was it because of that chest incident?

Worse, Ao would be nearly impossible to approach. Unaware of her own naturalness, shifting between violence and wisdom, mature one moment childish the next - a chameleon of emotions.

Still... if she favored boys...

"Ah! That might work," he suddenly realized, slapping his knee in triumph.