Although this has been explained repeatedly, it will be reiterated here.
The Holy Grail War.
It is a localized ritual led by a local Magus family in Japan, occurring in a city on the remote eastern island nation.
To obtain the All-Wishing Machine—the Holy Grail—seven Magi summon seven Servants to battle one another in the modern era. The final surviving Master-Servant pair wins the Grail.
Since the first Holy Grail War was held in Fuyuki City, five iterations have taken place. While each War ended in extraordinary circumstances due to various factors, among these five, the Third Holy Grail War undoubtedly caused the most severe consequences.
And the reason is simple.
Because it occurred during World War II.
In a global conflict waged for world hegemony, no one could remain untouched—not even the Magi who had hidden in the shadows of the world for millennia. Under the machinery of the state, many Magi abandoned their original quest for the Root and instead embraced grand ambitions of world domination.
If it served victory in war, anything could be used—with this mindset, in 1943, the Japanese military, which had suffered continuous defeats in the Pacific Theater, turned its attention to the Third Holy Grail War in Fuyuki City, seeking to petition the Grail to reverse their strategic losses.
Their allies, Nazi Germany, also took keen interest.
The involvement of these two great powers suddenly elevated the importance of the Third Holy Grail War from a mere "local magic ritual" to a new kind of war capable of altering the future trajectory of nations.
Yet this critically important war ultimately failed.
No—more accurately, it vanished.
At the peak of the Third Holy Grail War, all Servants abruptly disappeared, along with the Greater Grail, which vanished from Fuyuki City. Neither the Mage's Association nor the Church could trace any remnants. After months of investigation, they could only conclude that the Third Holy Grail War had been forcibly interrupted.
Due to this sudden interruption, the three founding families suffered devastating losses. With the global situation as it was, neither the Church nor the Mage's Association could act further. In the end, no party gained what they sought.
"—Except the one who acquired the Greater Grail."
On a speeding train, seated opposite Angelica near the window, Naoki explained to her everything he knew about this Singularities—and the reasons behind its current state.
"There were four parties involved in the Third Holy Grail War. Excluding the Church, which acted as overseer, there were effectively three. Of the three founding local families, none emerged with any gain after the War. Excluding Nazi Germany, which was embroiled in the European battlefield and couldn't interfere much here, only one party had the capability to move the Greater Grail out of Fuyuki unnoticed…"
The Imperial Japanese Army.
They alone possessed the resources and secrecy necessary to relocate the Greater Grail without detection. And the only logical destination for such a concealment?
Tokyo.
Or, as it was known then: the Imperial Capital of Japan.
The very heart of Japan—and its safest location. To hide something as critical as the Greater Grail, there was no better place.
This is precisely why Naoki now sat aboard this train—it was headed toward the Imperial Capital.
Since both Mifune City and Tokyo lie within Japan, the journey required little time. However, when Naoki and Angelica entered this Singularities, they happened to materialize aboard this very train—so they decided to ride it.
Of course, they did not purchase tickets.
"And after hiding the Greater Grail for two years, perhaps once they finished studying it—or discovered how to weaponize it—they reactivated the Greater Grail. Whether due to some hidden function within the Grail itself or simply fate, the Third Holy Grail War—which should have ended two years ago—suddenly restarted in the Imperial Capital."
"I suspect the Imperial Army itself is somewhat confused by the current situation. But since the War has resumed, they must follow its rules. From their perspective, this isn't about claiming the Grail—it's about protecting it."
"Well… none of this really concerns me—but—"
Raising his hand, Naoki stared at the crimson Command Spell etched onto the back of his palm like a blade, sighing helplessly. "You've really given me a job. I never intended to participate—why did you pick me so hastily?"
Command Spell.
The mark of a Master chosen by the Greater Grail.
Almost simultaneously with Naoki and Angelica's arrival in this Singularities, this symbol appeared on his hand—as if forced upon him, terrified he might flee.
"Then, Natsukawa-sama." Angelica asked, "will you summon a Servant? If needed, I can immediately provide a sacred relic. Among my treasures, regardless of which Servant you wish to summon, I can instantly supply the corresponding relic."
As Angelica said, with countless Noble Phantasms stored within the Gate of Babylon, she could summon any Servant imaginable—this was essentially directed summoning.
But Naoki shook his head. "No need. We aren't lacking in combat power. Summoning any Servant wouldn't matter… Besides, I already have a choice."
"What matters more than summoning a Servant is understanding the nature of this Singularities. What I just described—the true historical context—isn't merely fiction. It actually occurred in a specific parallel world, constituting 'historical fact' to some degree, part of humanity's broader timeline. Normally, such an event would never generate a Singularities here."
"So… the anomaly exists because of the Grail?" Angelica clarified. "That's what you mean, Natsukawa-sama?"
Naoki nodded, then smiled. "Yes. No matter what the anomaly is, it doesn't matter. With you and me here, we can even restore a shattered world."
"Thank you for your trust, Natsukawa-sama." Angelica replied respectfully. "Then, Natsukawa-sama—should we eliminate the enemy forces already in motion?"
"Ah, that…"
Slightly tilting his head, Naoki glanced at the door directly ahead of them.
The next second—
*BOOOOOMMMMMMMM—!*
A deafening explosion and violent rumbling erupted outside. The carriage they occupied was instantly filled with thick smoke. Fortunately, there were no other passengers besides themselves—so Naoki didn't need to bother rescuing anyone. (Though if there had been, he still wouldn't have bothered.)
Amidst the swirling smoke, heavy footsteps approached.
A figure emerged before them.
A silver knight clad in thick plate armor, wielding a long spear.
"Angelica, handle it."
After a single glance, Naoki waved his hand dismissively, as though shooing away a fly.
"Don't be too rough. Don't destroy the train. There's still a route to the Imperial Capital."
"Understood, as commanded."