Author's Note:

I do not own Mahouka Koukou no Rettousei or the Fate/Stay Night franchise. This story was written solely for entertainment, and was edited by ChristmasForJuan, who also aided in the creation in some of the new magics.

Also while the story will start with developing the background of the Fate/Stay Night cast, the main focus will remain on Tatsuya. For all those who are interested, I encourage you to use this prologue for any of your own Fate/Stay Night crossover fan fictions to explain how they moved to another universe.

The world was collapsing. The sound of churning earth and collapsing rocks reverberated in the near distance, each passing second amplifying the volume of the approaching void. The culmination of all their efforts had finally resulted in the destruction of not only the corrupted Grail, but also the entity that existed within it, the entity that brought forth the corruption in the first place. At the very center of what was left of the world, four figures awaited the end. Neither surprise nor fear painted their faces. They had known the consequence of erasing the Greater Grail from existence, putting and end to the wicked rituals it called forth, and ending the evil that heralded the extermination of mankind. One of the four figures, a red-haired adolescent body, observed the world's collapse while ruminating through his thoughts.

He did it. He had finally become what he had always strived for; a Hero of Justice. He had managed to save the world of the murderous curse that was Angra Mainyu, and saved innumerable lives in the process. However, this victory came with a heavy price, a price that he, now that the battle was over, started to doubt was worth it. With him were three girls. These weren't mere high-school friends or classmates, but people he considered to be the most precious to him. They had fought, laughed, despaired, and cried together … and now they would die together as well.

Looking down at Illya's fragile body that he cautiously held in his arms, a strange thought crossed his mind. Despite being older than he was, she would insist on referring to him as her Onii-chan. Shirou considered that this may have been a tragic remnant of the scars Kiritsugu's disappearance, or rather the fabricated lies that labelled his exile as betrayal, left in her tender heart. She had long since discovered the truth, but it was only natural for injuries of the soul to take longer to heal.

"I am sorry Illya, I shouldn't have dragged you into this, I should have been able to prevent it. This wasn't supposed to happen, not like this…", Shirou apologetically pleaded, his tears framing Illya's faint smile.

Though faint, it showed not a single trace of regret. The light in her eyes had already begun to fade.

"It's ok Emiya-kun", Shirou looked up and met with captivatingly azure eyes.

"We knew that it was going to end this way. If anything, I should be the one apologizing. For years I purposefully avoided Sakura, thinking that she was happy, that my father had made the right decision. But in the end I was just trying to convince myself because I was afraid to face the truth", supporting Sakura's body much like Shirou held into Illya, Rin regretfully regarded her sister's unconscious expression.

"I should had been a better sister, should have never trusted my father. But now is too late. All I can do now is be with her until the end and hope that we can be sisters again in the next life, only this time I will make things right and care for her."


The weak voice startled both the girl in red, and the boy opposite her.

"Sakura!" was their instant reply.

"I am sorry for everything…", she whispered in the same weak voice.

"You should have left me behind. Because of me all of you are going to.."

"Shhh", Shirou interrupted her with a gentle tone before Sakura started sobbing.

"It is all right Sakura. We are here of our own free will, and believe me when I say that I would prefer to be with you right here and now than in any other place in the world. After all… you are the people I cherish most…"


"Emiya-kun is right. Besides, we already have too much regret in our lives, there is no need for any more", Rin assured with a fond expression.

"Toh-… Nee-san. What you just said … about wanting to be my sister again… do you really mean it?"

There was no need for verbal confirmation, as Rin simply assured Sakura with a resolute nod. That alone was enough for tears to blur her vision.

"Me too! I also want to be your sister again. I want to be with Senpai and Illya-chan again, I want us to be together in this life and the next. I don't want to be separated from you again."

It was at that moment that an earsplitting noise forced their attention back to their unavoidable predicament. The collapsing world had finally caught up to them. A strong gust of wind accompanied the splitting earth and lifted everyone off their feet. It was now or never. Dragging every shred of remaining energy from his broken body, Shirou traced the heaven's golden chains, Enkidu, and used a single swing to bind the four of them together. Surprise was prevalent on the Tohsaka sister's faces when they witnessed Shirou's final act of defiance.

"I may not been able to do anything about what is going to happen, but I can make sure that we will all be together when the end comes!"

That single verse echoed infinitely in the blackened void that was nothingness, and just like that, the world had ended.

Unknown to the trivialities of mortals, two greater entities observed the unfolding events with great interest. One distinguished itself as the planet's enduring survival instinct, while the other … was slightly more infamous, though that subjective evaluation may differ from person to person.

Gaia, the representation of the plant's will, if not the not the planet itself, had been paying close attention to the fight that shouldered the fate of all living organism's survival, and welcomed the defeat of Angra Mainyu, the personification of all evil, with joy and pride. Kaleidoscope, summoned by Gaia to this ethereal plane for the purpose of cementing this defeat within all dimensions to prevent Angra Mainyu's victory over life, seemed unfazed by this course of events. Kaleidoscope had likely already expected this outcome.

"Well, I have to give it to the kids, they sure know how to put on a show."

Kaleidoscope was slightly sarcastic but Gaia payed it no heed.

"I am grateful for their efforts. Thanks to them the other realities will have a renewed chance at facing Angra Mainyu, but I do regret their sacrifice", Gaia melancholically stated.

"You already interfered with their deaths, is it alright to involve yourself to this extent?"

"I've done three things. That wish of theirs at the very end … I felt that the least I could do to reward their efforts and fulfill it to the best of my ability, though I don't know to which extent I can alter fate. Second is the body of that sad child. With that unnatural body structure of hers eating away at her life force, it would be too pitiful to die at a young age even after all my efforts. Lastly is Angra Mainyu's influence on it's host. His influence tainted her body and mind, so I cleansed her of his corruption and freed her from the Grail within her. Alas, all I can do now is hope that they will find happiness in whatever life they find themselves next."

Gaia, seemingly satisfied with her efforts, stepped back from influencing the laws of the world and returned to her passive state of rest. She had done all she could, and the fate of the world would continue with it's normal course.

That is, if it weren't for the additional presence still active in her realm.

"Wait until their next life to see the next chapter of their history? Hell no."

Kaleidoscope selfishly complained with a dark tone chilling his non-existent expression.

"Those kids provided me with the best entertainment that I had in years; such entertainment can't be easily found in most realities after all. There is no way that I am going to wait a lifetime to see what happens next! Oho~ especially with this new reality I found. A world where there is no border between magic and science … now this ought to be entertaining!"

Kaleidoscope looked towards the spot where the heroes had supposedly been swallowed by nothingness, and revealed the Boundary Field containing them. Enkidu had somehow persisted to exist and continued to link the four together, as if honoring it's user's wish to remain connected to his friends. The peculiar thing about this Boundary Field was that it trapped it's contents in a space between realities, and with their presences having seemingly vanished, Gaia had assumed that they had successfully started their reincarnation process. In fact, Kaleidoscope intentionally sent them to the rift between realities in a successful attempt to fool Gaia.

Gazing at the children before him, Kaleidoscope couldn't help but voice his thoughts.

"A world where magic and science blend together as one and where magi no longer need to hide themselves. Seems to be entertaining enough. On special with those strategic class, I wonder how those strategic class will react with magus at the level of heroic spirits"

Moving towards the center of the four magi, Kaleidoscope regarded golden chain that linked them together.

"This chain as well as Gaia's help… Fufufu, it's almost too easy", Kaleidoscope chuckled sinisterly.

"Enkidu, the chains of the heavens that can bind gods, I wonder what will happen if it were to continue to exist in a conceptualized state…"

Suddenly the projected chain, that was already on the verge of collapsing, burst into a myriad of golden iridescence and sought shelter in the bodies of the four unconscious mages.

After this was done he turns to see where Sakura and Illya were. "Gaia, I thank you for showing me how to change the core of a person magic circuits, but now I am a little curious, I wonder if I will be able to do the same and what to do, Oh well because I can waste too much time I will just see what happen if I take a set of their core magic circuits" after that he proceed to rice both hands up and on that moment the bodies of the young heroes moved their chest out and on that instant three spheres of light come out of their chest and remain floating in front of them, the ones in front of Rin were red ones, the ones in front Illya were yellow ones, the ones in front of Sakura were green ones and the ones in front Shirou were blue ones. After a few moment they moved to Kaleidoscope hands where they started to flutter for a moment until they stopped and then moved back to be in front of the young magus, but this time they didn´t have the three spheres of light of the color that come out of their chest, this time each of the three spheres of light were of different colors, one coming from each of the other young magus that were unconscious, and a moment after that the spheres of light got inside their chest.

"All right with this they've joined not just their fates but also their very cores along with their Magic Circuits. I am not too sure what will happen with things having turned out like this, but I am sure that it will be interesting! Now just one little stop before you can see your new home", the embodiment of eccentricity, visibly pleased with his work, murmured to himself.

There were two things associated with trans-dimensional travel. The first, if he simply placed something into a different reality, then much like visiting a neighboring city, you would have no history or knowledge of the world. While it would have indeed been grandiose entertainment to see how the heroes before him would try to make sense of the situation, he refrained from doing so this time due to a rare feeling of empathy he felt for them, and thus settled with for his next best plan. Secondly, he had learned from Gaia that the self-correcting mechanisms of the worlds always keep a certain balance, regardless of the dimension, meaning that if Kaleidoscope were to simply toss the youngsters into a new reality from Gaia's realm, the fabric of that reality would be rewritten to welcome their arrival, assimilating them into it. He only needed to act quickly so that Gaia wouldn't notice and prevent him from doing so. With a final compulsory glance over the floating bodies before him, he tossed them out into the foreign world.

It was early in the morning and the soft rays of sun tickled the seventeen year old boy sprawled out in his king sized bed.

"That really was a strange dream" Shirou yawned before once again burying his head in his pillow to appease his tired mind, which would have been successful if not for the radio alarm that had turned itself on in that exact moment.

"Good morning on this beautiful day. Today is December 12, 2088 and the social unrest in …" Shirou mind didn't pick up the rest of the newscaster's report as his mind stubbornly clung to a vital piece of information.

"2088!? What kind of joke is that?"

As the surprise woke his mind, Shirou realized that he wasn't even in his own room, as it was way too big and luxurious to be his. Getting up from bed, he walked towards the windows of the eastern wall of his room to see a somewhat familiar looking forest. Searching for more clues to his current predicament, Shirou came across a series of framed picture on his desk. One depicted his foster father Kiritsugu, and an even younger version of Illya carried by a woman that … very much looked like an older version of Illya. Shirou's befuddled mind couldn't come up with a better explanation when…

"Irisviel… mom?"

That single thought lingered in his head before Shirou could realize the implications.

"Wait a minute, how do I even know that?"

Shifting his attention to the next picture, Shirou hoped to make sense of his memory of an unknown woman, and his subconscious recognition of her as his mother. The adjacent frame showed his father once again, as well as the one he referred to as mother, Illya and himself. Judging by his facial features and height, Shirou judged himself to be eight years old. The relaxed atmosphere that could be felt even through the protective glass of the picture frame implied that this was likely to be a family trip.

"What is the meaning of this, I haven't even met Illya before the war, right?"

Shirou tried to deny the existence of the memory … but at same time he recalled the events clearly after spending just minimal effort into remembering them. What was going on? As Shirou eyed the last three pictures on his desk, more memories flooded into his mind like a leaking dam, one of which involved his father, mother, Illya and himself spending time together in a living room lit by the comforting glow of an antique fireplace. This time however, three other people joined them in the photograph, two of which he knew all too well.

"Rin … Sakura?" Shirou absentmindedly muttered.

Still, this was wrong. Regardless of the visual evidence, there was no possible way he knew Illya, Rin, and Sakura ever since he was a child. It would have been another story if they had met by chance before his adoption, but these pictures blatantly suggested that they had visited him and Kiritsugu on a regular basis. But that simply wasn't true. Still not too sure what to make of this, the final person on the picture caught his attention.

"Auntie Aoi?"

Just as he had done before, the name of woman he was not supposed to know rolled off his tongue in a well rehearsed manner. As if he was used to calling that name. Frightening as it was, it wasn't just his muscles that remembered that name, as he a soothing sense of familiarity permeated his cautious mind. Did … did he know her after all?

On yet another picture he could see Rin, Sakura and Illya dressed as fairies, Rin donning red, Sakura green, and Illya yellow colors, while a younger version of himself could be seen wearing a silly Robin Hood costume next to them. Again, memories of an event that he had never experienced, was never supposed to experience, came to his mind, as well as the supplementary information that that event was in fact a costume party they had attended in primary school. The final picture showed the main gate of an imposing mansion that he recognized as the very same mansion Illya resided in while participating in the 5th Holy Grail War.

"Wait a minute, Illya too?"

Focusing his attention on the unfamiliarly proportioned girl, he noted that Illya looked more like a 16 year old version of her mother rather than an older version of herself … though that may just be because Shirou had officially placed Illya in the "eternally a little sister" category and therefore had a hard time picturing her as anything but. However, as soon as that preconception flashed through his mind, it just as suddenly disappeared without a trace. At a frighteningly fast pace, Shirou accepted the "new" Illya, as if it had been strange for her to look any different. The taller and well proportioned Illya leveled up from her little sister appearance and assumed the spot of "responsible elder sister" … as hard as it was for himself to actually accept that realization. To be fair, she was technically older then him, but regardless of that, it would be hard for him to completely throw out his previous evaluation of Illya's character. His off-track thoughts finally coming to a stop, Shirou noticed a note left on the picture.

"First day of National Magic University Affiliated High School… Wait a minute, Magic High School?! What the hell is going on here?"

It was in that moment that Shirou was assailed by an overwhelmingly nauseous headache, while new memories flooded into his mind. If the dam had previously leaked, it had now completely broken down, causing him to be drenched in foreign memories that were and were not his own. It took several minutes for the pain to stop, ending with Shirou's mind completely assimilated to this new world. His previous memories hadn't been replaced, rather he simply received new ones. Both were true, and both were his own. While he could not make complete sense of it, he was able to understand it, though a sense of confusion lingered on.

As soon as the pain subsided Shirou decided that he won't receive all the answers by just walking back and forth in his own room. While he somewhat had a general grasp on the existence of "Emiya Shirou" in this world, he was unclear about the circumstances that caused this phenomena, so he decided to leave his room and talk to the one person that he could rely on most in such a situation. If his new memory was to be trusted, he would not need to walk too far in order to find her. Just as he made the first step out of his room, he was already met with the sight of Rin, Sakura and Illya waiting by her side.

"Rin, Sakura, Illya. I am so glad that all of you are safe!" Shirou genuinely exclaimed, not even trying to hide his wholehearted concern and relief.

The fact that each of them were dressed in their nightwear did little to dim his emotional outburst, nor were they particularly surprised that Shirou himself was still dressed for bed

"If you are this loud already then it must mean that you are fine", the seemingly nonchalant response couldn't completely distract from Rin's reddened cheeks.

"Senpai, I am so glad to see that everyone is safe after what happened. If something were to have happened to any of you because of me, I-"

Shirou interrupted Sakura, as had become a common recurrence between the two, to assure her with an amiable smile.

"You do not need to worry about that Sakura. Didn´t we tell you that no matter what would happen, we would never abandon you?"

Their reunion was thus completed. They were all safe and sound, and most importantly, together. Shirou could think of nothing that could ruin this perfect moment … except …

"So Shirou, don't you have something to say to your elder sister at all?"

The source of the voice was easily traced to the fair haired beauty in front of him. Despite having previously spotted this "form" of hers in a picture in his room, it was a completely different experience to experience her gorgeous beauty from up close. Standing in front of him was not the Illya he knew, but an Illya that had appropriately aged into the body of a 16 year old.

"You … look different but in a a good way." Shirou decided to play it safe in the presence of the two other girls beside him.

"It's true, even I was surprised when I saw you like this. What happened? Or actually … well now that I think about it it's only natural for you to look like that after all, right?", Rin questioned, being at odds with her conflicting memory of Illya's appearance.

"No I feel the same. I was just about to ask Illya myself", Sakura chimed in, agreeing with her sister's claim.

Illya briefly fell silent as she reorganized her thoughts to come up with a believable answer. While she was in the same position as her friends, at least she was somewhat aware of what was going on with her own body.

"I believe it's because I am a complete human now."

Seeing that her curt statement caused more confusion rather than alleviating it, Illya continued with her speculation.

"As you probably know, my mother was a homunculus meant to be used in the 4th Holy Grail War. One of the physical characteristics of a homunculus is the absence of growth, or rather, we do not age like normal humans do. Our bodies usually remain as they were when created all the way up until our death. Since my father was a human, I became a somewhat unique existence. Only half of me was a homunculus, so I was able to grow from my infantile state to my adolescent body, but that was the limit of my physical development. In fact, I am a few months older than all of you. Continuing this logic, the fact that I am aging like a normal human being is most likely … because I am. It's just a feeling but my body is definitely different, and those … memories. They agree with my theory. In this world, apparently, I am a human."

Ending her explanation on that note, Illya noted the brief period of inaction displayed by both sisters due to the magnitude of the information she had just offered. Taking advantage of this opportunity, Illya promptly ignored the two and turned her whole body towards the equally confused Shirou. Pursing her lips to form an alluring smile and adapting a posture that allowed unobstructed view and emphasized her already well-developed feminine curves, Illya whisper in a low purr.

"What do you think Shirou? Do you want to find to just how human I am now?", despite the adulterous nature of her invitation, a hint of her usual childishness was still noticeable in her approach, however, it was debatable whether or not this only empowered her attack.

Shirou's skin turned indistinguishable from his reddish hair as he received the full brunt of Illya's unexpected advance. Before he could come up with a plan of escape, and unexpected ally in red dashed forward and smote the innocent predator on the forehead.

"Ouch that hurts! What was that for Rin?!", Illya vibrantly screamed while caressing the center of her forehead.

"That is what I want to ask you!"

As usual, both parties threw their respective tantrums and the familiar arguing voices filled the halls just like they used to in Fuyuki. However, unlike in the private Emiya household, they were interrupted this time.

"I see that you are as animate as always", a new presence announced herself with a lecturing demeanor.


Once again, everyone except Illya seemed to only experience disorientation for a mere instant, before coming to the understanding that they somehow knew the person in front of them, despite having never met that person before.

"What, do I have something on my face?", Sella asked to break the uncomfortable silence, her tone both playful and stern.

"No, it's just that we all had a strange morning, that is all." Sakura quickly stepped in to prevent any further suspicion.

"Well, you better hurry up once you are done with whatever you are doing. Your parents are already in the kitchen and Leysritt … well you know how she gets when she is hungry", for Sella this was a common scolding she repeated day after day, which therefore led to her completely missing the bewildered reactions of the four children as she turned around to return to the kitchen. (Isn't it a bit weird for Sella to specifically tell them to hurry up and eat breakfast, but then leave without bringing them along? I guess she could have been busy?)

Their parents … were here? How was that possible? As there was no way to discover any answers to their questions by remaining in the hallway, Shirou, Illya, Rin, and Sakura decided to head towards the mentioned destination.

With each step they took on the path that was somehow clearly mapped out in their heads, bits and pieces of information revealed themselves to them, starting the with history of the mansion that was owned by Emiya Kiritsugu and Emiya Irisviel. They had met during the wartime period when Kiritsugu had traveled to Germany, which had been attacked by the Bella-Russia alliance, to provide humanitarian aid to the Japanese forces. The attack was eventually subdued but collateral damage was unavoidable. It was during that time that Kiritsugu met Irisviel. Irisviel was the youngest daughter of a wealthy aristocrat, and at the same time, the only remaining member of that bloodline. Her family had been killed during the attack and Irisviel was the sole surviver along with two relatively young girls that used to be employed as maids in the Einzbern household. They had merely met by chance, but as if mimicking a fairytale, the two of them had fallen in love shortly and conceived their first child but a year after. However, tension in Germany refused to be eased, which prompted Kiritsugu to suggest to his newfound family, plus maids, to move to his home country to lead a more peaceful life. It was back in Japan where Illya was born.

Kiritsugu was a passionate magical engineer and Irisviel herself possessed a degree of undiscovered brilliance and talent in the magical field that was previously undiscovered. Combining their intellects and resources, the ambitious pair eventually founded AvalonTech, one of many magic based technical companies in the area. With the generous earnings that AvalonTech brought them, Kiritsugu decided to purchase a mansion much like the one Irisviel used to live in back in Germany to make her feel more at home in a foreign country. However, as if disaster planned to follow them even across the continents, six years after they had settled down, a giant explosion went off in the middle of the city, a disaster that was thought to be orchestrated by the Great Asian Alliance to slow down magical progress of Japan by targeting the more prominent magic oriented companies in the area. Regardless of that, Kiritsugu and Irisviel, along with many other magicians in the area, used their talents to save as many lives as they could, one which was a young boy on the verge of death. Thanks to their efforts, he immediately received appropriate medical attention and was able to survive the catastrophe, though the same could not be said for his parents. Feeling bad for the orphaned child, the married couple decided to adopt him and name him Shirou. Just like that, Emiya Shirou was reborn into the Emiya family.

However, if this was the official Emiya residence, then why did Rin and Sakura reside here as well? Whether by coincidence or fate, Aoi, their mother, and Kiritsugu befriended each other at a very young age and had maintained a cordial relationship ever since. It was one day, when the Tohsaka twins were 9 years old, that Aoi stormed into the Emiya residence with both of her children, pleading for help. Apparently her husband, Tohsaka Tokiomi, had intended to trade Sakura who was born mere seconds after her elder twin, to a rather influential family of the Hundred Families called the Matou, a family with a rather suspicious background from practicing the arcane arts, in exchange for a specified amount of research data. What prompted Tokiomi to act the way he did were the results of Rin's and Sakura's magic aptitude examinations, which ended in extremely unfavorable results.

As a member of the 100 Families himself, Tokiomi sought to maintain the Tohsaka reputation and thus decided the research data of the Matou to be more valuable than the life of his second born daughter. Hearing this dreadful tale, Kiritsugu and Irisviel immediately assured Aoi that they would whatever they could to protect herself and her daughters from any ill will, and shelter them for as long as was necessary. The very next morning, Tokiomi arrived to convince Aoi to return to him, but after a repeated denial, the situation escalated in conflict and resulted in Tokiomi's swift defeat. Tokiomi unleashed a continuous stream of insults directed towards the former women of his household, a spectacle witnessed by Rin and Sakura from the windows of their rooms, before he left the family grounds. It had taken a full month for the required documents to be filed and submitted, but Tohsaka Aoi eventually became Ito Aoi once more. Tokiomi was never seen by them again.

With their memories having caught up to this point, Shirou and Illya eyed the Tohsaka, nay, the Ito twins with a concerned look. As much as they tried to hide it, it was easily noticeable to the recipients of the stare.

"I have stopped referring to that man as my father a long time ago", Sakura coldly stated with contempt directed towards her former father.

However, as fast her her expression sharpened, it immediately softened to display genuine look of concern.

"Though I am still not so sure about how I will react when I see Ao.. mother again…"

"Whatever happens will happen. What matters is that we will face it together this time", Rin gently assured, nudging Sakura in the back to keep her feet moving forward.

Agreeing with Rin's statement, Shirou and Illya did no more than confidently nod in Sakura's direction.

Together, they came to a halt before a door. A door that would undoubtedly lead them into a dreamworld that had become reality. If heaven really existed, was this it?

Locking eyes with each other to to shake off the remaining traces of hesitation, the group came up a unified agreement. No matter what lay behind this door, no matter the consequences of their actions, they would brave it together. A mysterious wave of strength flowed through their bodies as they made up their minds in unison. With a final nod of agreement, the four of them crossed the threshold of the door with a single step. Just one mere step that marked the beginning of yet another grand adventure.

In the next chapter:

Reunions. Adapting to their new lives and testing their new powers.