On a stretch of frozen land somewhere in Germany stands an ancient castle, sealed year-round by snow, ice, and a magical Barrier.
This is the home of a legacy abandoned by the disciples of the Third Magician, the Homunculus family known as the Einzbern.
Though the humans who created them have long since vanished from the world, the Homunculi have never forgotten the great ambition their creators once pursued with unwavering devotion.
The revival of the Third Magic.
To turn that miracle into reality, they journeyed to the distant Far East two centuries ago and forged an alliance with two Magi there.
Thus began the Holy Grail War and the lineage of the Three Founding Families.
It is now the end of 1993, and the sixty-year cycle of fate is about to begin once more.
Having suffered a devastating defeat in the previous war, the Einzbern have made unprecedented preparations this time, intending to stake everything on this single attempt.
The chapel of Einzbern Castle.
Beneath stained-glass windows depicting the long, wandering history of the Homunculi's pursuit of the Holy Grail, two figures stood in conversation.
One of them had dazzling silver hair that flowed down to her waist, and eyes as crimson as burning flames.
Her pure white dress could not conceal her full, graceful figure. Her refined beauty carried both the innocence of a young lady and the mature elegance of a noblewoman.
She was the Master representing the Einzbern family in this war: Irisviel von Einzbern.
The history of the Einzbern family dates back to the year 1 AD, spanning over two thousand years.
Across those long centuries, a single, unrepeatable miracle was born by chance.
Known as the "Saintess of the Winter," Justeaze Lizrich von Einzbern possessed the ability to effectively wield the Third Magic.
And now, there was Irisviel, a young woman who had reached the pinnacle of the Einzbern lineage on a different plane from Justeaze.
She was the ultimate masterpiece born from two thousand years of accumulated Homunculus craft.
Her performance surpassed expectations, completed a full decade ahead of schedule, and like that Saintess, she was likely impossible to replicate.
If even she failed to obtain the Holy Grail, then the Einzbern would willingly abandon their millennia-long wish and bury everything beneath the raging snow.
Standing across from Irisviel, her conversation partner appeared slightly smaller in stature.
At first glance, her flawless, androgynous face could easily be mistaken for that of a handsome blond boy. But upon closer inspection, a delicate feminine charm could be seen beneath her composed and dignified presence.
The strongest trump card prepared by the Homunculus clan for the Fourth Holy Grail War, Saber.
King Arthur, Artoria, stared at the item presented by the maid and asked:
"Irisviel, this is…?"
The silver-haired Homunculus gave a mischievous, almost childlike smile.
"Saber is pretending not to know again. You should understand better than anyone what this is."
Saber hesitated for a moment, then nodded.
"This is the catalyst you used to summon me into this world, the scabbard of the Holy Sword."
"Correct! Saber really is a clever child!"
Irisviel clapped happily, but Saber frowned, her expression turning stern.
"Please don't treat me like a fool, Irisviel."
"Sorry, sorry, just joking. Don't be upset."
The scabbard of Excalibur, King Arthur's most renowned weapon.
Merlin, the King's Magus and Type-Moon's foremost prophet, once left behind a famous saying:
"What is truly powerful is not the Holy Sword itself, but its scabbard."
If that statement is true, then the scabbard may even surpass the Holy Sword of the Planet in power.
According to legend, King Arthur lost the scabbard due to a treacherous scheme orchestrated by her sister, the Witch Morgan.
Just as expected, without the protection of the scabbard, the king was soon slain in battle during the rebellion led by his son, Mordred.
At the sight of the long-lost scabbard, Saber was filled with mixed emotions. At that moment, Irisviel spoke.
"I plan to let Saber use it."
"…Huh?"
Saber's emerald eyes widened in disbelief.
"But… didn't we agree that the scabbard would be used to protect you?"
After nearly half a year together, she had come to understand that her Master was a willful, imaginative young lady who delighted in novelty.
But wasn't this decision a little too rash?
Irisviel nodded.
"That's what Great Grandfather said. He said protecting the Lesser Grail is the top priority.
But after thinking it over, I still decided to give it to Saber.
Because, you see, the scabbard can only truly display its power in the hands of a king, right?"
In truth, she was hiding something.
The reason the Einzbern had not entrusted the scabbard to Saber was not to use it for protecting the Master, but because they were wary of Saber.
After all, the Three Founding Families would ultimately have to sacrifice their own Servants. Naturally, they could not hand the strongest scabbard to the strongest Servant.
What if they failed to kill her in the end?
A King Arthur protected by the scabbard would be invincible in both the literal and physical sense.
Irisviel had also concealed the dark truth of the Holy Grail War from Saber.
She felt deeply guilty about it, but even so, she still chose to trust Saber.
Even if it might be called naive, Irisviel believed that Master and Servant should trust one another.
With six enemies still ahead of them, how could they hope to win if they were already thinking about turning on their own Servant?
Saber thought it over again and again, but ultimately shook her head.
"I don't think Acht would agree."
But then her Master spoke, her expression unusually serious.
"This is a battle between Saber and me. It has nothing to do with Grandfather."
"You'll be scolded later, you know?"
"Then you can be scolded with me, Saber. Hehe."
"..."
Saber did not know the true intentions of the Einzbern family, but in her Master's crimson eyes, she saw boundless trust.
Artoria accepted the scabbard and spoke a simple yet heartfelt vow.
"Irisviel, I'm truly glad you are my Master. I swear upon my sword that I will protect you until the very end."
"Mm, thank you."
The silver-haired Homunculus smiled in return.
"I feel the same way, Saber… I'm really glad you are my Servant."
...
...
Today, Einzbern Castle was finally freed from the storm of snow after a long time.
Though the sky had not fully cleared, the milky-white light was far brighter than during a snowfall.
At her Master's enthusiastic invitation, or rather her clingy insistence, Saber was dragged out of the castle, and the two walked together across the endless snowy field.
Perhaps their earlier exchange had opened their hearts. Even Saber, who normally never pried into others' private matters, spoke up on her own.
"Irisviel, what do you want to do after the war ends?
Not the Einzbern family's wish, but your own."
"A wish…"
At the question, the silver-haired Homunculus came to a stop.
Saber did not yet know that Irisviel would never live to see the end of the war.
Even if they were fortunate enough to defeat all six opposing teams, she would still have to become the final sacrifice of the Holy Grail alongside Saber.
Though I have no future, just for this moment, let me indulge in a small dream.
Irisviel spoke the wish buried deep within her heart.
"It's less a wish, and more of a dream.
Saber, I want a child."
"…Ugh."
Saber showed a clearly troubled expression.
Although she had no interest in the topic of raising children, she did not want to spoil the princess-like Master's mood, so she followed along.
"You want to become a mother, Irisviel?"
"Mhm."
The silver-haired Homunculus nodded, her expression full of longing.
"A cute girl would be wonderful. Even if she's a little mischievous, that's fine, but…
Hehe, a lively yet steady boy also sounds nice."