As mentioned before, although Medea was affectionately nicknamed "Caster Mom," at her core she possessed a thoroughly girlish heart. She adored cosplay culture and even harbored dreams of getting married like an ordinary young woman someday.
Though Medea herself wore a cloak day in and day out—so much so that she rarely even showed her face—in her private room she secretly collected all kinds of outfits.
To Medea, these clothes were all irresistibly fascinating. Unfortunately, she had always believed her own figure was far too voluptuous; wearing them herself would never look "cute."
That was why, when Ren Kuroda made his suggestion, Medea cast a sidelong glance at Saber.
And that single glance was all it took for her to fall completely…
Saber was practically Medea's ideal incarnate. Petite build, flawless looks—someone like her could absolutely pull off those beautiful outfits Medea had been hoarding.
"Well… since Caster is an enemy Servant anyway, and Saber is technically on the same side as us, a temporary cooperation isn't entirely unacceptable…"
As Saber watched the previously uncompromising Medea suddenly light up, staring at her with shining eyes, an ominous feeling crept up her spine.
Tempted by the prospect of a living dress-up model, Medea ultimately granted Saber the "honor" of entering Ryūdō Temple. As for everyone else, they were not afforded such privilege—Medea promptly kicked them all out.
To be honest, watching Medea's face flush with excitement left Ren Kuroda genuinely puzzled.
Logically speaking, Sakura Matō and Rider Medusa made sense—they were both extremely well-developed and firmly in Medea's category of "too mature."
In Medea's aesthetic sense, that type was firmly classified as "not cute."
But Rin Tohsaka wasn't that far off from Saber, was she?
In terms of looks, the Tohsaka heiress could easily match Saber, and while Rin might have had a slight advantage in figure, the difference was hardly dramatic. Yet Medea had rejected her outright.
Ren Kuroda couldn't quite understand why Medea had fixated on Saber alone—but clearly, Rin simply wasn't her type.
Objectively speaking, Saber was probably the most universally popular Servant in the entire Holy Grail War.
Among the Servants seen so far, the King of Conquerors admired her martial prowess, and the King of Heroes later seemed to take an interest in her as well.
Lancelot pursued her relentlessly, even willingly degenerating into a mindless Berserker. Bluebeard worshipped her as a saint. Now even Medea had fallen.
Add to that Mordred—Saber's "daughter"—who had barged into the chaos, plus her complicated ties with Archer Emiya, and it could be said that nearly half the Servants in this Holy Grail War were connected to Saber in one way or another.
Ren Kuroda's plan to lure out Caster was simple.
Medea would pretend to coerce Saber into wearing all kinds of bizarre outfits, then use her magecraft to broadcast those images across every corner of Fuyuki City.
Naturally, due to Medea's spells, only those whose magical energy met a certain threshold could see these projections.
That threshold was set at B-rank or higher.
Which meant that even most Servants wouldn't qualify. These images were practically custom-made for Caster alone.
As a Caster himself, Bluebeard's magical energy couldn't possibly be below B-rank.
So when Medea's familiars scattered throughout the city, the constantly hunting Caster—and Ryūnosuke—noticed immediately.
Driven by intense curiosity, Caster intercepted one of Medea's familiars and extracted the image it carried.
Within the projection, the saint he yearned for appeared—clad in an outrageously revealing cat-eared outfit.
Beside her stood Medea, draped in her cloak, holding a long whip, looking every bit like she was in the middle of "disciplining" her…
It had to be said—Medea really knew how to enjoy herself.
Now that she had obtained a life-sized Saber figure, she was clearly having the time of her life, practically trying out her entire collection on Saber.
With each costume change, Medea meticulously crafted a little backstory, solemnly declaring that it was all to make Saber appear even more humiliated—so that Caster would surely take the bait.
Unfortunately, Ren Kuroda could see right through it.
She was just having way too much fun.
"This should be enough, right…? If Caster really is that obsessed with me, then what we've done so far should already be sufficient, shouldn't it?"
As Medea enthusiastically rummaged through her wardrobe again, holding up two particularly playful outfits and comparing them against her, Saber—reduced to a life-sized figurine—finally reached her limit.
She had agreed to help Ren Kuroda, and changing into a few strange outfits—though damaging to her dignity as a king—was still within acceptable bounds.
But as time went on, Medea became more and more excessive.
She even pulled out a wedding dress in the end.
She was a knight of Britain, for heaven's sake—someone who had taken a queen as a wife and somehow even become a "father." How could she possibly wear a wedding dress?!
When Saber firmly refused to cooperate further, Medea could only give up.
Still, the earlier barrage of outfit changes had thoroughly satisfied Medea's girlish fantasies. She even secretly took a full set of photos, planning to keep them as treasured memorabilia.
"Ren Kuroda, once Red Faction's Caster is eliminated, let's keep Saber here.
Using my Noble Phantasm, Rule Breaker, I can forcibly seize control of her from her Master.
Your cooperation with them is only for dealing with Red Faction's Caster anyway, right?"
There was no doubt about it—after obtaining a life-sized Saber, Medea had completely fallen for her and was now seriously planning to become her Master by force.
"That's way too underhanded, isn't it?
Didn't you say it yourself before? With your current setup—plus my strength and Mr. Kuzuki's support—our chances of winning the Holy Grail War are already very high. We don't need to cooperate with anyone else at all."
Hearing Medea's proposal, Ren Kuroda covered his face, utterly speechless.
Looking across the multiple routes of the Fifth Holy Grail War, Medea's obsession with controlling Saber was practically unwavering in every single one. Even now, with the plot completely derailed, "Caster Mom" clearly hadn't changed her mind.
"What's the problem? Saber is called the strongest class for a reason. Wouldn't having her as our ally make us even stronger?"
Medea's tone turned slightly embarrassed as Ren Kuroda threw her own words back at her.
But after spending so much time with Kuzuki Sōichirō and Ren Kuroda, she also knew that more often than not, they indulged her various whims.
"Tch. Don't give me that 'strengthening our forces' nonsense. You're just lusting after Saber's body.
Let me tell you, Medea—Saber is bad luck incarnate. Letting her join us would bring nothing but trouble."
Looking across every route of the Fifth Holy Grail War, Medea usually enjoyed smooth sailing in the early stages, often making it well into the latter half.
Then, in the Fate route, she declared she wanted to control Saber, directly angered Gilgamesh, and promptly got herself and Kuzuki killed.
In the Unlimited Blade Works route, she successfully seized control of Saber—only to be ambushed by Archer Emiya's feigned surrender shortly afterward, earning another fatal ending.
And in the Heaven's Feel route, she was outright killed by Saber herself.
Not to mention—how many people were eyeing Saber, really?
Even ignoring Lancelot and the current Caster, Mordred was still waiting in the wings.
All things considered, Ren Kuroda firmly believed that with his current lineup alongside Medea, there was absolutely no need to cling to the protagonist's coattails. As long as they weren't catastrophically unlucky, their odds were quite good.
Meanwhile, on the other side, Caster—having seen those images—was, unsurprisingly, furious.
Anyone with eyes could tell that he wasn't an idiot. He could clearly see that these magical projections were deliberately spread to lure him out.
And yet, despite knowing this, Caster still chose to step into the trap.
Not because he had lost his intelligence—but because his obsession with Jeanne d'Arc was far too deep.
Much like Lancelot's fixation on King Arthur, it had become a consuming obsession.
Jeanne d'Arc was his faith. His light.
He would not allow his saint to be defiled in the slightest.
Admittedly, Caster had to concede that the outfits she wore earlier were… quite beautiful.
But at the same time, he firmly believed that Medea's actions were humiliating the sacred saint.
Only a nun's habit was proper attire for the saint.
Those clothes Medea had forced her to wear were nothing short of heresy in Caster's eyes.
They knew of his obsession and were deliberately provoking him—clearly confident in their preparations.
But Caster was no fool.
Even as he burned with urgency to rescue his saint, he would not act without preparation.
The sacrifices from earlier rituals were sufficient.
His Noble Phantasm—Prelati's Spellbook—had finally met the conditions necessary to summon its strongest entity: the sea monster.
Once that legendary creature, capable of effortlessly destroying an entire city, was summoned, Caster was absolutely confident he could rescue his saint.
From the familiars scattered across the city, it was easy to tell that the Servant who had captured his saint was also a Caster.
Their plan was obvious—to lure him into their territory and eliminate him using positional advantage.
After all, in the Holy Grail War, for the relatively frail Caster class, a well-prepared stronghold was their greatest weapon.
Even so, Caster remained utterly confident.
Because once the sea monster was unleashed, let alone a single Caster from the Blue Faction—even if they had three or four Servants together, Bluebeard would not fear them in the slightest.
After all, the sea monster's power rivaled that of top-tier Servants.
It could grow stronger by endlessly devouring living beings.
And most importantly—
If it wasn't completely destroyed in a single strike, it possessed terrifying regenerative abilities.
It could regenerate endlessly.