Skipping ahead to the final battle against Ivan the Terrible.
Clearing the Russian Lostbelt could be described as both incredibly easy and nightmarishly difficult.
Takumi's diary provided some intel on the Lostbelt King. While it kept Ritsuka and her team from going in completely blind, the actual utility of the information was extremely limited. For the most part, they still had to stumble their way through the frozen wasteland, figuring things out as they went.
Following a relatively standard Singularity-clearing progression, Ritsuka had managed to recruit several rogue Servants: Billy the Kid, Beowulf, and Atalante Alter. After surviving numerous harrowing battles and life-threatening adventures, they had finally arrived before the Lostbelt King—Ivan the Terrible.
However, there was a massive deviation from the original plot.
Because Takumi had relied entirely on [Independent Manifestation] to clear the Singularities, the original Chaldea had never manufactured the critical Mystic Code known as the "Heroic Spirit Portraits." Lacking this vital piece of equipment, and cut off from Chaldea's main power supply, Da Vinci and the others were completely unable to find the necessary materials in this frozen hellscape to construct a proper Servant summoning circle.
(Author's Note: Summoning Heroic Spirits outside of a Holy Grail War isn't a standard or easy process in the Nasuverse. Chaldea spent years just to successfully summon Da Vinci and create Mash. The Fuyuki Holy Grail War relied on the Third Magic. During the Incineration of Humanity, they had the massive power output of the FATE system backing them up. In the Lostbelts, they relied on the Heroic Spirit Portraits. None of these were "normal" summoning methods.)
Consequently, Avicebron was never summoned.
Without him, Ritsuka lacked the absolutely crucial Trump Card—the massive [Golem Kether Malchut]—required to physically restrain and grapple with Ivan the Terrible's colossal mammoth form.
Furthermore, a certain dimension-hopping vagabond, Miyamoto Musashi, hadn't randomly drifted into this Lostbelt either...
Missing two incredibly vital pieces of combat power, even with a fully synchronized Demi-Servant Mash holding the line, the situation was grim. While Ritsuka possessed an uncanny ability to perform better under extreme pressure and hadn't issued a single bad command since arriving in Russia... making it all the way to Ivan the Terrible had basically pushed her to her absolute limit.
Defeating a Lostbelt King boasting power equivalent to a Chief God required more than just flawless tactics. If you fundamentally lacked the raw combat power to even stand in the same ring as them, all the clever strategies in the world wouldn't change the outcome.
Adding insult to injury, Kadoc—who had actively guided Ritsuka's group to fight Ivan—was currently standing on the sidelines with his Servant, Anastasia, deliberately conserving their strength... The completely inexperienced Ritsuka was genuinely out of options!
"ROAAAAAAR——!!!"
The Thunder Emperor bellowed furiously. Raising his massive, mammoth-like trunk, he called down apocalyptic lightning from the sky, bathing the surrounding frozen wasteland in blinding blue-white light.
Clang, clang-clang, clang...
A furious, despair-filled melody echoed from the high balcony of the royal palace, piercing through the roar of thunder. Driven by the musician's absolute hatred and sorrow, the music flooded Ivan's ears, aggressively attempting to erode his sanity and suppress his colossal physical vessel.
[Dio Santissimo Misericordia de mi (O Lord Most Holy, Have Mercy on Me)]!
This was the Noble Phantasm, the absolute musical masterpiece, belonging to Antonio Salieri!
"You dare attempt to erode my mind...!"
Hearing the music—which felt like a constant, agonizing reprimand specifically designed to forcibly dredge up his deepest guilt—Ivan roared in agony. Clutching his massive head, he redirected the apocalyptic storm of lightning he had been gathering directly toward the palace.
He was fully prepared to obliterate his own royal palace, along with Salieri inside it!
"Oh no! If Mr. Salieri gets taken out here, we'll lose our only chance!"
Realizing the impending disaster, Ritsuka felt her stomach drop.
The Russian Lostbelt was born from a sudden, apocalyptic global freeze 450 years ago. The average temperature was minus one hundred degrees Celsius. Only humans who had undergone brutal genetic modifications to become the wolf-like "Yaga" could survive in this hellish environment.
But because every waking moment was a desperate struggle for survival, physical strength had become the only metric of value. Concepts like "entertainment" or "art" had been completely eradicated. The piano Salieri was currently playing was literally the only instrument left in the entire Lostbelt.
If he abandoned his post to dodge, not only would the critical debuff on Ivan the Terrible instantly vanish, but he wouldn't even have an instrument left to play!
But the sheer disparity in combat power was insurmountable. If they wanted to block a concentrated lightning strike capable of vaporizing an entire palace, their only option was...
Ritsuka instinctively looked at Mash standing beside her.
"Senpai! We absolutely have to protect Mr. Salieri!"
Gripping her massive shield tightly, Mash's eyes burned with unexpected, fierce determination.
The attacks from Atalante Alter, Beowulf, and Billy the Kid were practically scratching the paint against Ivan in his peak, enraged state. Salieri's Noble Phantasm was the absolute prerequisite for even scratching the Emperor.
"...Right! Let's do this together!"
Ritsuka forced down the rising panic in her chest. Looking into Mash's violet eyes, she nodded seriously.
Without hesitation, the two girls sprinted directly into the path between Ivan the Terrible and the palace.
A short distance away, Kadoc—who had been subtly commanding Anastasia to harass Ivan—watched them run into the line of fire, momentarily stunned.
But he quickly snapped out of it, shifting his gaze toward the armored Shadow Border parked in the distance.
He knew the Doctor's true identity. The entirety of Team A knew it now.
If he wanted to fulfill his own hidden agenda, he absolutely had to force Romani to reveal his true form. The power of a Grand Caster—even if he currently lacked the Grand Spirit Origin—was a strategic asset he desperately needed to factor in.
And realistically, he had to admit: without expending his Sirius Light Command Spells, there was almost zero chance Anastasia and the rogue Servants could defeat an enraged Ivan the Terrible.
Therefore, even if Mash and Ritsuka miraculously managed to block this ultimate attack, the power of King Solomon was absolutely vital to securing the final victory!
As for whether Romani would actually step in? Kadoc knew the answer with absolute certainty: He absolutely will!
Because the Doctor was exactly that kind of frustratingly self-sacrificing idiot.
***
Exactly as Kadoc predicted, inside the Shadow Border, Romani—who had been intensely monitoring Ritsuka's movements on the screens—was already standing by the airlock, ready to launch himself out of the vehicle at a microsecond's notice.
No one should ever doubt if Romani actually had the capability to intervene. At his core, he was the King of Magecraft, Solomon. While he might not possess the overwhelming, world-ending power he had during his prime Servant days, restoring his original Spirit Origin as Solomon wasn't impossible for him.
Granted, if he forcefully reclaimed his Spirit Origin now, he would manifest without a single Noble Phantasm, his summoning formulas would be entirely ineffective, and he wouldn't possess any of his ten rings. He would literally only have access to raw, unadulterated Magecraft...
But even with only that fraction of his true power, it would be more than enough to support Ritsuka and tip the scales.
Romani stared unblinkingly at the live feed, his tightly clenched fists slick with cold sweat.
He had completed every necessary internal preparation to reclaim his Spirit Origin. All it took was one final, conceptual step, and Solomon would officially manifest in this Lostbelt. Everything hinged on a single thought. It only depended on whether he was truly willing to do it.
...It was true. He genuinely loved living as a normal human. But if the situation demanded he finally shoulder the absolute responsibility of his past, he wouldn't hesitate for a single second to sacrifice that dream!
Furthermore, he considered this his absolute duty—a necessary penance to honor the boy who had silently carried the apocalyptic burden that was originally meant for him...
He absolutely refused to cower when it mattered most.