Part 1: Prelude

Prelude


Dawn

"Let's review the facts," the scholar said to me. "Earth scientists have hypothesized so-called 'parallel worlds,' other versions of Earth and its surroundings, expanding indefinitely like mirrored reflections. If true, that would mean that Earth has not only one future, but many. In other words..."



"Think of it like this. The 'you' that you are aware of exists somewhere upon this timeline."

"It might sound unreal. Humans aren't equipped to perceive, let alone traverse, the 'wall between worlds.' But what if I put it another way? Think of these parallel worlds as other possibilities."

"Imagine what might have been in your life. Think of the connections that were cut off and thrown away. Options you see now, in retrospect, that you would never have considered at the time. Picture how your life today might be different had those 'what-ifs' come to pass. All those variant futures, in everyone's lives, make up the vast array of parallel worlds."

"Your actions, those of the 'you' in this present moment on this particular timeline, can change the world in any number of ways. That proves such possibilities are alive, and that your world is on the 'proper axis'."

"Conversely, a world where the future cannot be changed, regardless of your choices, can have no parallel worlds. Such a world is nothing but a dead end, solitary and singular, with a past as immutable as its future."



"This is a necessary evil, a byproduct of the way parallel worlds are structured together. After all, a world where humanity made radically different choices would bear very little resemblance to the world you know."

"Some worlds may have crumbled by making all the worst choices. Other may have made all the right ones, and rocketed ahead, perhaps too far ahead. In either case, that world can no longer be said to resemble ours, and once a world moves out of sync, it is no longer 'parallel.'"

"'Why would those worlds become solitary,' you ask? Could the people in those worlds not still make different choices?"

"Unfortunately, no. This dimension contains a finite amount of energy, and has none to spare for creating new worlds from the worlds gone so far astray."



"If parallel worlds continued to increase in this manner, their number would eventually exceed the capacity of this dimension. Parallel worlds must exist, but in a manageable quantity. By my own rough calculations, and judging by the civilization of Earth alone, this solar system would collapse within 100 years if the parallel worlds expanded without limits."

"Seeing as how we do, in fact, live and multiply, the solar system is clearly not oversaturated with possibilities at this time. I extrapolate that this dimension can sustain our existence for the next 100,000,000 years."

"The system works thusly: At regular intervals, the dimension takes stock of the possibilities it contains, and only allows certain outcomes, those that would not cause undue difficulty in managing the next generation, to remain. As for the unneeded parallel worlds, the system closes off their futures."

"Specificially, every 100 years, it calculates how many worlds will last another 100 years, and supports those worlds only. Have you heard of the Law of Conservation of Mass? This could be called the Law of Conservation of Events."





"And so, the civilizations in these numerous parallel worlds line up with one another. Think of it all as a giant tree. Only the trunk at the center can grow tall. The branches may bear fruit, but eventually they reach their limit, and fall without reaching the future."

"You understand, yes? There are no parallel worlds for a world that has evolved too fast or crumbled too quickly. Such worlds are merely dead ends whose outcomes are predetermined."

"And so, there is a set time frame in which these branches are trimed, extra possibilities are removed, and future histories, once fluid, turn to stone."



"Such laws apply to the Moon Cell as well. The Moon Cell is a self-updating observatory, which continues to record every incident and possibility on Earth. You could say it makes the same observations on parallel worlds. It's all quite vexing."

"But in any case, the so-called Foundation of Humanity governs the Moon just as it does the Earth, tracking the various spiritron worlds and determining where their futures will come to an end."

"Once one passes that event horizon, there is no turning back, nor turning aside. Any lingering 'ifs' become 'might-have-beens.'"

"It is the work of a great invisible hand...no, of a god's invisible hammer. I have named this point in time 'the Quantum Timelock,' the event compilation set by an absolute observer."











...I vaguely remember being there for that long lecture. I passed through a deep, deep darkness for so long I felt my consciousness fade. To the end of SE.RA.PH. And then I set foot into the forbidden territories, where even the light of the Moon Cell could not reach.



Beyond this wall is the Zero Dark, the domain of the Umbral Star fragment that flew in from space and burrowed into the Moon Cell. Normally, a system manager like myself would never be able to go there. But your assistance has made it possible. ...Are you at peace with this? You know that SE.RA.PH must be protected against all external threats. This is the responsibility of the one who bears the Regalia, the prize and the burden for the victor of the Holy Grail War. Understand?



I understand that you're worried. After all, your opponent is an incomparable monster. But rest assured. The Regalia is on your finger. You hold the power of the Moon Cell itself. You need only focus on deleting the monster inside.

I nod in agreement, and look up at the wall again. ...It's huge. SE.RA.PH has its giant structures, but it's still rare to see anything on this scale. The bizarre architecture gives me the impression of a prison, capable of holding tens of thousands of prisoners.

I feel an urge to touch the wall. It's hard as diamond, but smooth as silk. Normally, SE.RA.PH only builds objects out of the same materials found on Earth. The touch alone tells me this stone came from somewhere else. There's no doubt this belongs to an invader, something from beyond Earth, made from pseudo-spiritrons. Just as Archimedes said, it's an external threat.

...I'm afraid. Anyone would be. Inside this place sleeps a monster who nearly destroyed both the Earth and the Moon. And now they expect me, one lone wizard, to defeat it. If only Saber were here...

That's not possible. If we were to bring a powerful Servant here, the enemy would sense our intrusion. However strong or high-ranking a Servant might be, nothing from the Moon Cell could ever defeat the Vanguard of the Umbral Star. There's only one way to win. We must use the Regalia to slay the monster before it awakens. That's why you and I are here. Besides, you wouldn't want to waste your Servant's life in a hopeless battle, would you?

*nod*

*quake*

Wh-What was that...?!

The monster must be stirring in its sleep. ...Well, well. How perfectly horrid. But that also means I'm right. The enemy hasn't noticed just the two of us yet. This is our best chance to strike off its head. Let's sneak in through this breach. Please don't make a sound. ..Is everything clear, Hakuno Kishinami?

*nod*