Prologue part 3, The world we live in.

Tunk…! Tunk…! Tunk…!

The hammering echoed throughout the shed...

Tunk…! Tunk…! Tunk…!

The incandescent forge was alight.

TUNK!

"Watch out, kid!" said a rather older voice wisely, "One bad hit can ruin the blade."

"I'm sorry…" Shirou apologized; he was in front of an anvil. In one of his hands, he was holding a gripper, and it was holding a red-hot blade, while in the other, he was holding a hammer, which he was using to shape the blade.

Tunk…! Tunk…!

"That's what you have to do; use less force. You have to be firm; and steady," said the voice. Shirou was the only person inside the workshop, but the voice was clearly heard.

"I think it's ready, Grandpa Muramasa..."

"Then you know what to do," the latter replied.

Shirou nodded. He carried the blade to a basin full of heated oil. With great care, he submerged it inside it. After a few minutes, the apprentice blacksmith took out the blade that glowed with a whitish light.

The apprentice magus turned and raised the blade to analyze it with his Structural Grasp. Without having to wait for almost anything, the information came to his head: This can be considered a short blade, a short blade for a Japanese sword, to be exact. Other data also appeared in his mind, such as Its hardness, resistance, sharpness, among other things. Since the sword had just been forged, all of its stats were maxed out. His Structural Grasp told him next to nothing about its history, for obvious reasons. Finally, the information about the special properties of the blade came to his mind: Due to the materials used at the time of its forging, mainly the Onmyōdō talismans, the sword has gained a degree of effectiveness against evil spirits of Shinto origin.

"What is your assessment, grandfather?" Shirou asked as he showed the sword to no one in particular or, at least, so it seemed. If someone looked closely, they would observe how the boy showed the sword to... Another sword? More specifically, to his Muramasa katana.

The Kanji etched on the blade, by which the Muramasa surname was written, lit up as the same voice spoke again, "Hmn… Not bad for an apprentice blacksmith. It is nowhere near the less renowned swords of my era, but for someone who started forging a little less than a year ago, it's a good job. Although it will only be useful against evil Shinto spirits, use it against more than that, and its effectiveness will decrease greatly."

"Yes. That's what my structural grasp told me..." Shirou said, unable to fully get used to speaking with his sword.

He remembered how, a couple of months after obtaining the katana, something strange happened. Every night, he had increasingly lucid dreams about the forge and the mysterious blacksmith that inhabited it. He was able to talk to him more and more until, when his shed was restructured to be used properly as his workshop and he was able to start with his first job, the voice of his ancestor shouted at the redhead loudly...

"What the hell are you doing!? You don't even know how to hold that hammer well! You're going to break the blade! My spirit did not possess my last creation to see how you destroy a sword!"

To say that Shirou had been shocked would be an understatement. He almost ran out of the workshop. His father, for his part, was only somewhat surprised. The old magus killer had already inferred that the curse of the katana served to inherit the knowledge that his adopted son's family must have been guarding for years. Although he did not expect that Muramasa had been such a capable blacksmith that he even managed to impregnate his last sword with his spirit, managing, in this way, to transfer a part of it into the katana.

He had introduced himself as Senji Muramasa and, considering that the first Muramasa was Sengo Muramasa, he must have been the second or third master blacksmith. Saying that the sword he was possessing was the latest creation forged by Muramasa, there was no doubt that it was the third master blacksmith. Which made sense since the first master blacksmith had always been described as: 'A very skilled blacksmith, but with a violent and unbalanced mind, on the verge of madness; a madness that he was supposed to have transmitted to his blades.' So much so that it was believed that the katanas have a 'hunger for blood' and drove their samurai to commit murder or suicide. But the ancestor who was possessing the sword seemed to be a calm person. Perhaps he was somewhat crude but never reaching the point of being violent and unbalanced.

Senji explained to both of them what his goal was: to create the last and most powerful sword, the ultimate sword. An objective that he inherited from his ancestors and passed on to his descendants. He also told them how, just before his death, he saw his mission truncated by the passage of time. Because of this, using what was left of his strength, he created his latest work: A katana that served to transmit his techniques accurately to his descendants. Surprisingly, he put so much effort into creating the sword that, in the end, he ended up imbuing it with his spirit. Since then, he had dedicated himself to bequeathing his forging techniques to his descendants, as well as collecting the new techniques developed by them.

And now it was Shirou's turn.

The young redhead tried to introduce himself; however, to his surprise, Senji told him that it was not necessary, told him that he already knew him and that he had waited a long time to see him again.

The 13-year-old, now 14, did not know what his predecessor was referring to; however, for some reason, he too could sense that, indeed, they already knew each other.

Finally, the old blacksmith asked Shirou if he was willing to help him with his goal. And, to his own surprise, he was quick to make a decision. Inside himself, he was excited by the idea of creating such a wonderful weapon.

Kiritsugu agreed with the decision as his son's personality was distorted by the fire; and, this left his son empty, so, Kiritsugu feared what would happen after his death when Shirou had to be left alone. The boy had no objective, nothing beyond his desire to help people, which had been born as a form of penance for being the only one who survived the fire. That Muramasa gave his son a purpose, that Shirou accepted it willingly, was a blessing for him.

For a moment, the freelancer thought about telling him more about his dream. However, the instant he said the words: ally of justice, Irisviel's face came to his mind. Her deformed and agonizing expression as he clenched her neck, even if she wasn't the real Iri, was a clear reminder of what he had sacrificed to pursue his dream. He lost everything, his wife, his daughter, and killed more than 500 people without getting anything in return. All for chasing an impossible dream, beautiful, yes, but impossible. He never spoke of his dream in front of Shirou again. It was too much for him to be the source of the greatest evil that had ever been done to the child. He would not put an unattainable dream on his shoulders. The mere thought that, by pursuing that illusion, his son would end up in a way similar to his terrified him.

Kiritsugu entered the old shed, "Shirou! If you don't come soon, Taiga will make a mess by not having anything to eat."

That thought made the apprentice magus tremble, "I go!" Shirou took Muramasa, and placed him in his scabbard, then left his shed. Although not before giving his workshop a last look, they had managed to turn the old shed into a full-fledged forge in a way, he was proud of what they had accomplished.

The magus saw his son run into the kitchen and smiled slightly. 'I won't burden him with that curse, not even to put my corrupted soul at peace.'

The magus Killer knew that he did not have much time left, he believed that the scabbard had denied the curse of all the evils in the world, but it was not. Even if Avalon had managed to mitigate the effect, the scabbard was no longer with him, and without Arthur around, so little would be of much use anyway. In short, the curse began to take effect, but very slowly. Kiritsugu stifled a wry laugh, entered the last holy grail war to get the cup, and be able to make a wish, a miracle: The salvation of everyone in the world by creating a utopia. And precisely because the planet was dying at an accelerated rate, and that the magecraft was getting weaker and weaker and hence the curse as well, that this was what was allowing it to survive for a few more years, it was like a slap from the same fate.

He entered the kitchen. Taiga had already arrived and was sitting around the table in the room. Shirou, for his part, was finishing serving breakfast.

The redhead brought the food to the table, and the three of them sat down to eat.

"¡Itadakimasu!" All three said…

The trio ate breakfast while they watched television.

Seeing the news, Shirou frowned, "Kiritsugu... Do you really think that's the only option?"

Kiritsugu sighed, "I'm not sure, although it seems more and more that it will be. However, I want to believe that they will find an alternative that is less dangerous," he replied.

"It's hard to accept. Isn't it?" Taiga said dejectedly.

Both men in the room nodded.

The news they were seeing was about two researchers debating the current situation on the planet. It was already irrefutable that the planet was dying. Nor was it denied that the degradation that the planet was suffering was the fault of human action. At this point, there was no point in trying to disprove it. The degradation process accelerated more and more with the simple passage of time. Despite the measures taken by the different countries of the world to stop this disaster, apparently, it was already too late, as nothing was being effective.

Seeing the imminent extinction of humanity, all scientists in the world began to search for alternatives. That was where the idea came from…

The first thing they proposed was the colonization of other planets. And, although humanity had already reached Mars a few years ago, it would take many years to make an inhospitable planet habitable. Many more ideas came up; however, in the end, all the proposals had something that made them unviable, all but one.

This was the only idea still debated. Although the plan had already been put in place, and it was getting closer and closer to completion, a huge number of people refused to accept it, as it could have serious consequences. The most important consequence was having to leave the physical plane. In effect, this idea consisted of becoming digital beings inside a huge supercomputer discovered on the Moon. Project Moon Cell, they called it.

The Moon Cell was a supercomputer with such absurd processing power that it was capable of influencing reality. In short, it could create a miracle, the miracle necessary to save humanity. So, what was the problem? Easy, who should use it, and how? This was literally being debated right now.

However, the dominant activist family, the Harwey family, had prohibited any trip to the Moon. To prevent someone from reaching the Moon Cell and using him in the wrong way. This brought endless political conflicts and, together with the situation that was taking place in the world, created a situation of terrible decline.

"Do the two of you really have to go to England, Kiri, Shirou?" Taiga asked even more discouraged.

Kiritsugu nodded, "I have some business to complete in Europe, and for Shirou, a change of environment would do well for him."

Taiga muttered dejectedly, "I understand that England is one of the few countries that has been least affected by the current situation. But, even so, Fuyuki is also one of those few places that remain relatively normal. Can't you stay?"

Shirou smiled with a bit of pity, "Forgive us, Fuji-nee, but these are important business."

She sighed sadly, "I understand…"

"Forgive us, Taiga, but this is beyond us," said Kiritsugu before heading towards his son "Did you finish the training, Shirou?"

The redhead nodded.

He had been strenuously trained for a whole year in swordplay with Taiga, as well as the advice Muramasa gave him. He had also practiced his Reinforcement magecraft to exhaustion Kiritsugu made him beef up at least a hundred light bulbs daily. Besides, he had to analyze the structure of everything he saw, it was crazy, but he didn't complain.

He had also advanced in the use of Projection. Even though magecraft was generally useless due to the extreme consumption of mana when projecting. They discovered that when it came to any weapon that fell within the concept of a sword, the mana expenditure was greatly reduced. And not only that, Shirou could replicate anything that fell under the concept of swords with extreme ease, not only on a structural level, he could even replicate their history and abilities. The only bad thing was that these were a little weaker than the originals. Also, due to the influence of Gaia, the projections ended up deteriorating until they disappeared.

That the projections made by Structural Grasp were a bit weaker than the original ones made sense to the blacksmith and his apprentice; Kiritsugu was also able to theorize with relative ease the why of these things. Gradation Air could not project objects with 100% reliability, although there were ways to increase the faithfulness of the copy using various methods, such a; the better the image in the user's imagination, the more stable and durable the object. The projection also improves by having technical knowledge about its construction, such as, for example, things like having studied a plan or having materials that serve to superimpose on the desired shape. The main reason why the projections, in general, are weaker than the original ones is mainly that the image within the imagination of the caster is not as accurate as of the original object; however, Shirou didn't have that problem when it came to projecting swords, thanks to their alignment between their origin and element; however, the problem that he did have was the information that he could not obtain through Structural Grasp alone.

In short, to have a perfect projection, then you need a perfect image of the object in question. For this, you required as much information as possible, and structural analysis only provides information through sight. However, this led to a discovery...

Understanding the problem, Muramasa came up with an idea: If Shirou forged something and then replicated it with the Projection magecraft, then it should not become weaker than the original, because, when forging the sword, Shirou knew all possible information about its creation, thus being able to replicate it to perfection. Which they would later prove, and it would turn out to be true. However, thanks to this, they realized a new problem...

They called this new problem the Structural Gaps. These, as the name suggested, were holes in the structure of an object, flaws. These were produced by information that Shirou could not understand; an example of this occurred when he tried to project the katana that served as the receptacle of his ancestor, he could understand its physical structure with ease; but, what he could not understand, was the soul of his ancestor who possessed the katana. So when he projected it, what he got was a normal katana of excellent quality, albeit a bit degraded by lack of information, and obviously without the soul of his ancestor tied to its structure.

"Then get ready to go," Kiritsugu said as he got up from the table.

...

...

...

Finally, Shirou and Kiritsugu were ready. They had both packed everything they needed. Taiga and old man Raiga accompanied them to the airport. Before leaving, the two said goodbye, promising to return to the young teacher one day.

Thus, the duo got on the plane with their objectives very clear...

Wait for me, Illya. Before I die, I have to see you again. Even if it's just one more time... The magus thought solemnly.

Kiritsugu had to gather the materials and information necessary for an irruption into the Einzbern territory. As well as preparing Shirou as much as possible so that he could help him in the rescue.

Shirou, for his part, had two goals: Become strong enough to be of use to his foster father in rescuing his sister. As well as learning everything you can to create the ultimate sword.

They were heading straight for the wolf's mouth, they both knew it, but recently Fuyuki wasn't safe for both of them either.

The city was home to the Tohsaka, a powerful family of magi. The heir to this held the position as the second owner of the city.

There was also the Matou family, formerly known as Makiri. Although they were in decline, they were still a family with a long lineage of magi.

Then there was the Einzbern family. They had a property on the outskirts of the city.

And, most worrying of all was the following:

If the information provided by the magus killer's contacts was correct, then two families of magi had asked the Tohsaka for permission to reside in the city. Of course, this only in exchange for certain benefits. The families were: the Yggdmillennia and the Ainsworth.

None of these were little-known names in the Moonlit World. Furthermore, the Tohsaka was rumored to be also forming very close business ties with the Animusphere family.

Why were so many families of magi concentrating on the same city in an Asian country? The only thing that came to Kiritsugu's mind was...

No, that was impossible. Once the war ended, he himself verified how Fuyuki's thaumaturgical lines had weakened enough that it was not possible to perform the grail ritual again. In other words, Heaven's Feel was out of the question.

But then, why?

The magus killer shook his head. It was already too complicated having to deal with a single family of magi to have to figure out the meaning of the movements of five more.

He had to focus on the goal of rescuing his daughter. For now, it was what mattered most.

Thus father and son began their journey to one of the three great institutes for the study of magic, the Clock Tower.