A/N: I do not own Fate/Stay Night, Fate/Zero or any other associated works. Type-Moon and Kinoko Nasu do.

Diary Entry made on 12th December, 2000 AD. (1)

This is a story from six years ago. (2)

Truthfully speaking, I don't know why I am writing down the events of that Grail War. It was the place of my rebirth, if you could call it that, since Fuyuki was the place where I shed my old identity and face and adopted a different one. My time as the Master of Caster was the foundation of my current skill and aptitude as a Magus.

I have few friends amongst Magi, most of them too self-centred and egotistical for my liking. Since I have devoted myself to enhancing my Combat Skills, I am constantly looked down on by the Mages who seek the Root, no matter how revolutionary my research has been. Apart from Waver and [REDACTED], I have no friends in the Clock Tower. Moreover, recently I have received news that Kariya had died, primarily due to the damage done by Zouken Matou on his body. Emiya had died one year ago, fulfilling the promise I had made of him and extracting one promise from me before that.

I think that is why I am writing this down. Tomorrow I shall leave for Europe, where I will put my abilities as a Magus to the test. I have made all the necessary preparations. Both my and [REDACTED]'s experiments have proven fruitful, granting me a powerful Trump Card. While my control of the Weapon is not as good as I would expect, its very status as a Noble Phantasm would give me a distinct advantage.

Still, victory is never certain, and a plan never survives first contact with the enemy. Moreover, my opponent is several centuries old, so there is a very likely chance that I may die as well.

I have accepted that fact. I am not afraid of death. After all, to be a Magus is to walk with death after all.

Still, telling someone of my experiences of the Fourth Fuyuki Grail War would be nice.

...Even if that person is just my diary.

Let's see here, it all began with a serial killer in a dark room, trying to summon a demon for his amusement...

A flash of light burst in the dark, unlit room. The light was not overly bright, but in the darkness, it was probably blinding.

Dust had flew from the force of the incomplete ritual, creating a mist-like shroud. As the dust cleared, it became clear that the two occupants of the room had become three.

A lean, black-haired man of average height had appeared. Judging from his face, he was likely in his mid-teens. His blue eyes looked at the others in the same room as him. While his eyes passed over the child in the room with something akin to indifference, he stares at the older man with a mixture of confusion and fear which quickly becomes that of realization.

As you may have suspected, that man is me, your friendly neighbourhood protagonist.

I was naturally rather confused on my summoning, my thoughts at that time being a rather jumbled mixture of 'What the hell is going on here?', and 'Where the hell is here?' and 'Why am I here?'

Then my eyes fell on the scene before me.

The crying child on the floor, bound and gagged. The runic circle I was standing on, drawn in a bright red substance whose coppery smell told me it was blood. A redhaired man with a deranged look in his eyes, and a hunting knife in his right hand. This man's victims, two bloody corpses lying at the side...

While I couldn't remember what I was doing before, I was pretty sure that being dragged into the world of Fate/Zero was not in my schedule.

Still, I could worry about my current status later. Right now, I have a serial killer looking at me with a mixture of confusion and bad intentions.

For my health, that is.

Since I had never bothered to learn Japanese apart from the tattered bits and pieces I had learned via Anime and Manga and the occasional video game, I have no understanding of what he was speaking.

However, I did have an understanding of someone's intentions when they use their knife to try and poke you in the eye.

I quickly dodge his attack, only to be assaulted again by the knife. As I retreat even further behind, I was admittedly surprised by the speed and fury of Ryuunosuke's attacks. Isn't he supposed to be interested in killing only women and children?

Then he rants something in Japanese. I could roughly translate the words for 'Demon' and 'Death' but I think I understood what he was saying. He wants to try killing a demon for a change. I think.

Of course.

I survey the room before Ryuunosuke attacks any further. While dark, my eyes had adjusted to the darkness to a surprising degree. Most of the room was completely trashed and probably was that way, even before my summoning. The kid captured by Ryuunosuke was lying on the ground, unmoving and completely still. Probably unconscious. The exit is on the other side of the room, behind Ryuunosuke. Escape through there was impossible.

I could try to escape through one of the side rooms, but it was likely that I would end up trapping myself, since I have no idea where they lead to.

Which means fighting back is the only option.

Ryuunosuke was faster, stronger and slightly taller than I was. Moreover, he was attacking me like a wild animal, clearly with the intent to kill. However, I could use that to my advantage, since he was attacking without any kind of plan.

Apart from a few months in Karate, I had zero experience in self-defence. But I was in good shape, and my reflexes and reaction speed were superior to his. The first step to my victory would be to deprive the enemy of his weapon.

Before he could attack any further, I swiftly punched him, as hard as I could in his face. Dazed, he took a step back.

I grasped his right hand with my left. Twisting his wrist, his knife fell from his hand. I kicked it away with my left leg as far as I could. Startled by my sudden movements, he had no time to react. My other leg moved quickly, as I kicked his shin with all the force I could muster, causing him to collapse on the floor.

He may have been disarmed and vulnerable, but I knew that my safety was not ensured as long as he was alive. I knew that from our little skirmish, only one person can emerge alive.

I had every intention of it being me.

I walk over his slumped form and reached for the knife on the floor. Apart from a sound of shock when I punched him in the face, and another when I kicked him, he had not made a single sound. However, he had managed to recover and was right behind me as I picked up the knife.

I needed to end this quickly before he has a chance to disarm me.

Humans are incredibly fragile, with many things in this world capable of killing them. It is really easy for one to die. A weapon offers an immense advantage in combat.

Before he could react, I slashed Ryuunosuke Uryuu's throat with his knife.

Ryuunosuke's knife was not the kind used in kitchens and households. It was a high quality, hunting knife which is typically used in skinning deer and similar animals. It can cut through flesh like butter.

He slumped for an instant, blood pouring out from his throat, his carotid artery cut open from my attack. Then in the next instant, he fell, very dead, lying down in a pool, of his own blood.

Now that the threat to my life was disposed off, I could focus on dealing with my current situation.

I step over the corpse of my would-be killer, and kneel to check the status of the only other living person in the room.

The boy was eight, maybe nine years old. He was relatively unharmed, except for some small cuts and bruises and his unconscious state right now. I remove his restraints, and carefully leave him to the side, lying down on a carpeted portion of the floor.

I have to choose my next move very carefully. Between rogue Magi, Dead Apostles, the Holy Church, and other forces it is very easy to die in the Fate universe. My only weapon for survival is the knowledge and information I possess about future events and the like. And even that may be irrelevant due to the fact that the Kaleidoscope was a thing.

The safest place to be right now was probably Fuyuki, and since Ryuunosuke and Caster's kidnapping scheme won't exist now that Ryuunosuke is dead, it just means that I would have to avoid the Fuyuki Fire and that would be easily avoided since I could just avoid that half of the city.

But since Caster won't be summoned by Ryuunosuke it was equally likely that the new master of Caster would be someone even worse than him. Also I would rather like it if Angra Mainyu doesn't, well, kill all the humans. Since I am sort of counted in that number.

Which means that the best course of action would be to summon Caster myself and involve myself in the events of the Grail War. I could influence most of the events occurring directly and change the outcome of the War entirely.

Still, I would rather not get involved in the Grail War. Between Kiritsigu, Kirei and the Servants, there is a very high chance that I could die. And that's beside the fact that, well, I don't speak Japanese.

Maybe I could fake being an amnesiac tourist who got all his stuff stolen. That would probably the best way to get the heck out of Fuyuki as fast as possible.

And then the choice gets taken out of my hands. Because why not.

The back of my hand starts burning. I sigh, knowing full well what it would be. As I raise my hand and examine it, revealing three red marks forming a tattoo on my skin.

Command Spells. I have just been chosen as a Master by the Holy Grail.

And since Risei has aligned himself with the Tohsaka faction, I doubt forfeiting would be an option. It would be likely that I would die if I go anywhere close to the Church.

Which means I would have no other option but to take part in the Grail War.

I groaned in frustration. Still, there were worse ways to be introduced to the Moonlit World. The Fuyuki Holy Grail Wars isn't even that dangerous when compared to the Grand Orders and the Ultimate Ones from Notes.

And if I am to meet Zeltrech to find a way back home, being involved in this World is necessary.

I pick up the old and tattered book which had at one point belonged to Ryuunosuke's ancestor and began to go through it.

Thankfully, the book was written in English, with bits of German and Japanese mixed into it. It appeared to be some kind of introduction to the art of Formalcraft with several notes regarding the same.

Still, most of it is completely useless to me at this is point. What I needed were two things. The Magic Formula which was used in the Summoning of a Servant and the Aria used to do the same. I could have used the Circle I had appeared from. But the blood used to make it was wet and my landing there had smudged it. Moreover, blood from Ryuunosuke's corpse had tampered with the circle. It was for the best that I make a fresh circle and initiate the Summoning through there.

Taking another knife, I carefully make a small cut in my skin. From my brief reading of the book, I could tell that blood and a specially-prepared magic chalk can be used for the drawing of Formalcraft circles. Since the Summoning ritual does not require Magic Circuits or even an Aria in some conditions, I suppose it could be counted as Formalcraft. For such rituals using one's own blood is recommended as it would grant the greatest effect.

The Summoning is done not through the power of the Magus but rather the Power of the Grail. The actual Summoning is incredibly simple compared to the internal complex mechanics of the Holy Grail.

Drawing the Circle isn't too hard. It's just a series of intersecting lines inside a large circle. Having prepared the circle for summoning my Servant, I stand up and walk to the edge of the Circle, and compose myself for the Summoning.

The Magical Circle is the most important portion of the Summoning ritual. As long as the Circle is intact and the will to Summon a Servant is present, you may Summon a Servant. However, it isn't a 100% chance.

The Magical Circle is directly tied to the Grail's internal Summoning System. It behaves like a lock which must be opened or broken to Summon a Servant. Using the Aria for the Summoning is like introducing a key to the lock, and as long as the number of servants has not exceeded the limit, an appropriate Servant shall be summoned, depending on the presence and nature of the catalyst. Not using an Aria would be like breaking a lock. Forceful and direct, but not really feasible.

As I begin my chant, the clock strikes three. I couldn't help but think that I was forgetting something, but I put such distracting thoughts at the back of my mind. I will need to pay my full attention to the ritual. I stick my hand out over the circle drawn with my own blood and begin.

"Silver and iron to the origin. Gem and the archduke of contracts to the cornerstone", I muttered. The air in the room stopped circulating, creating an ominous feeling in the room. The summoning ritual had now begun, and the ritual circle has been connected to the Grail's Summoning System.

"The ancestor is my great master Schweinorg. The alighted wind becomes a wall. The gates in the four directions close, coming from the crown, the three-forked road that leads to the kingdom circulate."

The Circle is now generating Blue Sparks. I could feel something hot and powerful press against my body. It is a distinctly uncomfortable feeling.

"Shut (fill). Shut (fill). Shut (fill). Shut (fill). Shut (fill). Repeat every five times. Simply, shatter once filled."

A searing pain enters my body as I finish this portion of the Aria. It was as if hot, burning oil is being conducted through every blood vessel in my body. I bit my lip to prevent me from screaming due to the pain. The Circle glows brightly now, as if a small moon had appeared in the room. The light blue glow of the Circle lits up the room and strange shadows form on the walls.

I struggle slightly. I had not expected the Summoning Ritual to be so... tiring. It was as if my strength was being sapped away as I continue speaking the Aria. I could feel my Muscles being drained of all power. I gather my remaining strength and continue speaking.

"――――I announce. Your self is under me, my fate(doom) is in your sword. In accordance with the approach of the Holy Grail, if you abide by this feeling, this reason, then answer."

The light in front of me explodes. Earlier it was like a small moon but now it's like a bright star in front of me. I am nearly completely blind due to its intensity. A loud sound, akin to a raging tornado is heard by me as this occurs.

I nearly collapse from the pain. It was as if several dozen molten swords were thrust in my body simultaneously. This was not what I had expected as I attempted the Summoning Ritual. I idly think whether the other Magi underwent such torture or was it just me. My vision is starting to flicker. I think I might fall unconscious soon. Since I've come so far, I will need to complete the Ritual.

"Here is my oath. I am the one who becomes all the good of the world of the dead, I am the one who lays out all the evil of the world of the dead.

You, seven heavens clad in three words of power, arrive from the ring of deterrence, O keeper of the balance ――!"

I nearly shout the last parts out.

Then, it was over.

The phantom pains from the ritual disappear. It was as if they weren't there in the first place. The light vanishes as well, leaving the room shrouded in darkness again. I had collapsed on the ground, sitting on the floor as I stared at the Servant that I had summoned. My clothes were drenched in sweat and my vision was flickering. The fire burning under my skin had died down, and I took deep breaths trying to recover as I examined my partner in the conflicts to come.

She had a feminine figure, wearing dark, silky clothing which hugged against her body. She carried no weapons and an ebony cloak and a shadowy veil covered her head and face, protecting her identity. She felt like some kind of otherworldly figure and held herself with a strange, inhuman grace.

My head was throbbing, and I struggled to focus at the present. The Servant I had Summoned wasn't one I am familiar with, but someone different entirely. I could see that under that veil, her lips had curved into a frown.

Her mouth moved, but I couldn't hear anything. It was as if my ears had died from the strain of the Summoning.

She raised her hand and waved it slightly over my face. I could see, something happen but I couldn't see what.

Then, my strength came back to me. My muscles regained their power and my vision cleared, allowing me to see again. My hearing and other senses had returned as well. It was as if a massive weight had been lifted from my shoulders.

I shakily stand up, my legs still getting used to... whatever the Heroic Spirit before me has done. I turn my attention to her and notice that she was a bit taller than I was.

Beneath her veil, I could see that her expression was one of... disgust? She was sneering at me for some reason. I don't think I have given her any reason to be offended by me.

"Hmph. So you're the pathetic, waste of space Magus who has Summoned me. ", she speaks in a condescending tone. It is clear to me that this woman has no respect for me. To be fair, I have not given any reason for her to give me any respect, but still, she could be a little more cordial to me.

It would be unwise to anger a Servant. Even the weakest Servants can snap the average human like a twig. However, if I am to gain the respect of the Servant before me, I would need to gain her approval and present myself as an equal, if not her superior. Since her personality is somewhat arrogant, I would need to show that I am an asset to whatever ambitions she has in the Grail War. I only want to live and go home, so it won't be that much of a problem.

"I think you are mistaken. I am not a Magus, Caster. I have never been, before being involved in this Grail War."

"Don't lie to me, brat!", she hissed, her voice full of contempt. " I am a Servant who can only be summoned by an experienced Magus. Moreover your Circuits are of such high level that you could only have come from a Magus family at least a century old."

I blinked, registering what she said. "I have Magic Circuits?", I blurted out, surprised.

She examines my expression carefully for an instant. She frowns.

"Are you really not a Magus, boy?"

"No, I am not Caster. I know of the Holy Grail War and I know of the existence of Magi and the like, but I am no Magus myself.", I answer honestly. "I didn't even know I had Magic Circuits."

She stares at me for a moment before speaking, "It appears as if the Summoning had forced open your Magic Circuits. They seem as though they had never been opened before this day." She sighed. "It appears as if you're telling the truth."

She grimaced. "This is even worse. My summoner can't even defend himself from the other Masters."

"Hey!", I barked. "First of all, the fact that I don't know any Magecraft doesn't mean that I can't learn. And-"

" You're an idiot!", she snapped. "It takes years of learning and research to learn even a respectable amount of magecraft! There's no way you will able to learn anything of note during the War!"

"But still, I can try!", I spoke indignantly "Also, aren't you a little bit too hasty to conclude what type of Master I could be?"

She looked at me for a moment. I stared back, we had apparently reached a stalemate in our argument. I think I should take the advantage now, having hidden my trump card until now. Carefully choosing my words, I speak, "What if I told you, you will have an overwhelming advantage over all the other participants in the War?"

"What do you mean?"

"I happen to know a lot of things.", I hummed. "I know the identities of the various Masters of the War. I know which Servants they have summoned and what their weaknesses are. I know things about the city and the Grail no one else does."

With a small smile on my face, I spoke, "I know how to win the War, Caster. If you join me and are willing to work with me, then I will make every effort to ensure your victory."

Your victory. I had worded my proposal so that in face value it would appear that I was taking a subservient role to Caster. By indicating that the Victory will be "hers" and not "our" or "mine", I have relinquished all the fruits of our possible triumph onto her. That's fine though. I don't want a faulty Grail filled with All the Worlds Evils.

She stared at me for a second. Two Seconds. Three Seconds. Then she burst out laughing. I was admittedly surprised at her response.

"You clearly are something aren't you?", she spoke, giggling. She was obviously amused by my offer, for some reason. Why was she-?

"Oh don't make that face. I would like to think that you're a worthy Master for me", she smirked slightly under the Veil. "You seem intelligent and bold enough to propose such a thing to me... fine. I, Servant Caster of the Fourth Holy Grail War will accept you as my Master, however, if you don't fulfil my expectations, then don't come crying back to me later on."

I grinned. The negotiations had succeeded. "I have every intention of surpassing your expectations, Caster."

She nodded and we shook hands. It appears that Caster was a Magus of the highest calibre, having restored my stamina and energy with a wave of her hand. While I had no idea of her ability in combat, there were ways by which we could overcome that hurdle. Moreover, Caster is probably the best Servant I could have Summoned to amend my lack of knowledge about Magecraft.

Still, despite this small victory, I couldn't help but feel that there was something I was forgetting. Something very important.

Then, all of a sudden the door banged. A few voices shouted in Japanese from the outside of the house. All of a sudden, the door crashed open, its sound reaching us in the inner hall. A few guys wearing a police uniform charged inside, raising the guns, and pointing them at me.

Caster it appears has disappeared into her spirit form.

Ah. So this is what I was forgetting. The fact that I was standing in a place where a murder had taken place.

From that moment onwards, the Fourth Holy Grail War had officially begun.

A/N: Hello readers. This actually the first time I have written something on this site. Fanfiction has been my guilty pleasure for the last two-ish years, and I just wanted to sit down and write this idea. I have had other projects, but had dropped them all out of either lack of interest or laziness. The primary reason why I am here is to improve my writing skill so that I can begin working on my Original Ideas.

This Fanfic, apart from being my jumping pad into Writing is also me playing out my Personal Power Fantasy for a bit. While the Protagonist isn't going to be beating Servants any time soon, in its potential future sequels, there is every chance of this happening. I also intend it to be an exploration in the greater themes and worldbuilding of the Nasuverse.

It also takes inspiration from other Fanfics quite a bit. I am not the first to have my SI enter at this specific moment. And the idea that Ryunosuke's book was a Formalcraft guide comes from The Sage's Disciple if I recall correctly, probably the best Fic of its type.

While I may call it a 'Self Insert' that would not necessarily be true. While the MC and myself share several Characteristics, we also have several differences. I will elaborate as the story proceeds.

Nevertheless, I would like all of you to provide your thoughts on this. Constructive Criticism is appreciated, but please don't hate on me for the sake of hating on me. If your thoughts are particularly nasty, please keep them to yourself.

Also, if you would like to Beta for this story, please feel free to PM me. Though my response is dependent on the speed of my internet at the time. My area has a rather shaky internet connection.

(1) The diary in which this entry is being written has a special spell on it. It encrypts the writings within, making the words written on it appear like gibberish to anyone not knowing the decryption key. Moreover, the names of certain objects and people are shown as [REDACTED] since it would be easy to deduce their names from the context, for its writer at least. This is also the way I am avoiding potential spoilers for potential future sequels to this story.

(2)This part is directly inspired from the opening of the Prologue of the Fate/Stay Night Visual Novel. The VN is considered by many to be amazing and it is the best way to get into and enjoy the Fate franchise. It's a bit lengthy though. I have only just started playing it though, so I can't say any more than that.

Thank you.