DISCLAIMER: I don't own anything in relation to what I write, I either stole it off Wikipedia, the type-moon/fate wiki or I used my non-existent brain cells to produce this work (if you can even call it that). I probably stole some other stuff as well but we don't talk about that. Also I know crappy titles, It's a WIP.

Muramasa, commonly known as Sengo Muramasa, was a famous swordsmith who founded the Muramasa school and lived during the Muromachi period in Kuwana, Ise Province, Japan. He had created many blades, some of which were cursed. However he never intended them to ever be, what he did intend was to create the ultimate blade that could cut through anything. He knew however that he would not be able to accomplish such a feat in his lifetime. This is why he decided to leave his ambitions to his descendants in the hope that they would be able to accomplish what he could not. This is what inspired him to invest the rest of his life in making a magic crest.

Engraved on the body in a variety of shapes, most typically in a magic circle, a Magic Crest is a series of Magic Circuits that were given a more stable form in order to act as an archive of thaumaturgical capability. At some point in the magus' life, he will forge some of his own Magic Circuits into the Crest, store many, if not all, spells that he learned in life, and then pass it down to his successor. As the process repeats itself with each new generation, the older a lineage is, the greater the number of Circuits forming the Crest, and the greater the amount of knowledge stored inside it. It is the duty of any heir of a family of magi to successfully expand and pass down the Crest to the next generation

Muramasa had already delved into the mystic arts of magic several times in his life. His very forge was a combination of a skill known as territory creation as well as mystic codes that helped create the swords he is so known for. Therefore a magic crest that would allow him to give his descendants a head start should not be out of his reach.

Of course, this magic crest would be unique and one of a kind due to it not containing spells but instead the blueprints of swords and other such weaponry. Muramasa had decided that no matter how dull, sharp, cursed, mundane, or just outright failures the swords were, all would be inscribed into the magic crest. And these instructions were to be passed down to each generation.

After all one man's trash is another man's treasure.

And so our ambitious sword smith developed his own magic crest and passed it down to his son, and his son passed it down to his son. The magic crest was passed down for centuries and by the time it reached the 3rd generation of his descendants, the goal of creating a blade that would cut through all had changed. Instead of just being blades that should have been placed inside the magic crest other weapons were inscribed as well. These weapons included axes, spears, hammers, scythes, and even shields. All of which had their own special type of magecraft added to them so they could surpass their mundane counterparts.

However, as time passed the family name of Muramasa was abandoned due to lords and noblemen of the past sending assassins to end the line of blacksmiths. They wanted revenge because the cursed blades forged by the original ancestor had killed many important political figures of ancient Japan. Although it would have been easy for the lines of blacksmiths to cut down the noblemen and take their place, it would have taken too much time. The time they could better spend making weapons that would help them to reach their goal.

So they sacrificed their name but in exchange, they received something that would allow them to progress more efficiently than ever before, secrecy. With their name gone the long line of weaponsmiths could wholeheartedly focus on their goal and the efficiency at which they were progressing was astonishing. After many generations the term blacksmith was also abandoned, replaced by the label of magus. And now the most recent heir to the magic crest of Muramasa was held by a boy named Shirou.

Kritisugu Emiya had won the Holy Grail War that much was certain. From a magus point of view, his victory would be seen as one the greatest accomplishments one could receive. After all, that is why a magus such as Keyneth would enter the holy grail war. It was done in order to establish their superiority above the three great families of the Clock Tower. In sort in order to reach the root.

However, the only thing the Magus Killer could call his accomplishments was a disaster. As he walked along the now broken path that was once a peaceful neighborhood, he could only think of one word to describe it... Hell.

He started running along the broken road as if searching for something or someone that he could save. Anything that would allow him to atone for what he had done. Crumbling houses and dead corpses were all he could see as the black mud continued to flow out of the blue portal in the sky. Nevertheless, he kept searching, not wanting to give up after all he has sacrificed for his foolish goal.

"Plea..se he..lp me"

That was when he heard it, a sound for salvation that he longed to hear. It was coming from under the pile of stones near an almost collapsed house. He ran to the pile and dug through it hoping that it was not too late for whoever was underneath.

After digging for a couple of seconds he found a child. The child had red hair and a set of golden eyes. These eyes of the boy glowed with a determination to live and Kiritsugu Emiya was more than happy to grant this wish. He placed the boy down as gently as possible on the solid stone pavement. Then he said a single word and his stomach started to glow. As it was glowing a golden sheath came out and the man quickly put the sheath into the boy.

Golden lines started to form wherever the child was injured and as the lines glowed the wounds started to heal. This was the work of Avalon, the sheath of King Arthur's holy sword of promised victory, Excalibur. Even the curses that came from the grail were no match for the healing power of this EX level Noble Phantasm.

Although time was running the same as usual, the man known as Emiya felt as if it had slowed down just to torture him one last time. It was then all of his fears disappeared as the young redhead in front of him opened his eyes and stared into his. His frown disappeared as he picked up the young boy and gave him a hug. It was not so much for the boy, but more for him.

"Thank you, thank you, thank you. I am saved" was all the cold-blooded assassin could say as he continued to hug the boy that he didn't even know the name of.

Several days later

Kerry was walking back and forth from the corridor of the hospital, while his body wanted rest and relaxation his mind wanted to know whether or not his efforts to save the boy were rewarded. Just as he was about to go to get a cup of coffee the room the boy was in had shot open and a doctor came out with a smile on his face.

"Rejoice for your son is alive and in great condition, my friend," The doctor said as he came and tried to shake the hand of the former assassin. However, before he could the said man had already rushed past him and into the room before even correcting the doctor on his relationship with the boy.

As Emiya entered the room he saw it, he saw the very being that granted him his salvation. It took all it had in him to not go over and straight-up hug the child to death out of joy. So he took a deep breath, put on the most pleasant smile he ever could muster and started walking towards the boy in a manner similar to that of a close friend. As he walked towards the boy he noticed that he became aware of his presence and made eye contact with him. He slowed down his walking and when he reached the boy he went in a crouched down position.

It was clear that this staring contest would go nowhere so Kritsugu was about to get things started, but before he could the boy smiled and interrupted him. "My name is Shirou and the doctors said that you saved me, so I suppose I should thank you for saving me," He said in a formal tone

The Magus Killer, at first, blinked a couple of times and then felt amused at Shirou's attempt to start a conversation. 'It seems as if this boy whose name is Shirou wishes to be a leader in our little discussion' he thought and he gladly granted this wish of his. " My name is Kiritsugu Emiya, and there is no need to thank me Shirou for it is you who has saved me and not the other way around," He said in a tone that could only be seen as thankful.

Shirou raised an eyebrow but decided to go against his curiosity due to there being more important matters that needed to be discussed. "Well then I suppose the best I can do then is say your welcome then, but no matter how I see things it is you who has saved I'' He saw the man about to correct him or do something of a different matter so he decided to raise his hand so that he could continue. "I see that you want to argue against my opinion but before you do I need to know a few things. We can discuss who should be thankful to who later, ' the boy said.

Kiritsugu was once again amused by Shirou's royalty-like behavior, and this was when he asked the question that he wanted to ask the minute he saw the boy. " If you don't mind me asking how much you remember before the incident happened." Kiritsugu knew that the boy did not have all his memories due to him not providing his family name. And even if he did it would not matter due to him being the sole survivor of the great fire incident that took the lives of over 500 people.

Shirou looked at the floor for a few seconds while in deep thought and then opened his mouth and answered the question that was asked. " I can't remember anything that relates to my personal life. All I remember is my first name as well as how to interact with common people" He said in a very weak voice while drifting off into a trance like a state

Kiritsugu sighed because he didn't know what he should feel for the boy. Should he feel happy that the boy will not remember who died and that will mean he will not be sad for their deaths. Or should he feel pity for a boy who just lost the entirety of his childhood? That was when he decided to ask the question that would allow him to help the boy. "I am going to go straight to the point Shirou," he said in a kind tone that broke the boy's trance and made him look into the man's eye with the same pride and determination as to when he came in.

When he saw he got the boy's attention he continued. "As of right now you have two options from which you can choose. The first is that you can go to an orphanage alongside all the other orphans that lost their parents in the great fire. Or you can be adopted by me, a complete stranger you met today"

The boy looked up at the ceiling for a few moments and turned his head towards the man. And then spoke the words that made Kiritsugu's so-called cold-hearted heart melt. "I choose you," the boy said in a tone that sounded more like a declaration than a choice.

Kiritsugu went wide-eyed and had to suppress the urge to smile ear to ear. Then he took out his briefcase that he had put down and took out some documents. "Very well then. Let's get started then shall we?" he said in as much joy he could ever muster. "Oh, rights I should also tell him that as well…. Yes, it's better that he knows now than later" he muttered and he saw the boy looked confused at what he said.

He then paused and said, "You see Shirou, I am a Mage".

Several days later

When Shirou first asked his father to train him in the art of magecraft he had declined because he did not want his son to be a part of the moonlit world. However, after seeing Shirou perform magecraft and realizing that he was cannibalizing his nerves which could leave him crippled or outright kill him. The former mercenary decided that he should teach him so that he doesn't accidentally kill himself.

First, he needed to see his origin and alignment which was an easy task due to the black rod he took from his father when he had killed him. To say that the Mage Association would kill to obtain this rod was an understatement. It was one of a kind, it was one of the few mystic codes the Magus Killer ever cared for.

After using the rod in connection with a magic circle Kiritsugu Emiya had found out three things that left his jaw hanging.

The first was that the boy had the same origin and element alignment which was weaponry, this was even rarer than his dual origin of severing and binding. This meant that the boy would be able to surpass any magus in the field he was specialized in but it also meant that he would be completely unable to perform well in any other form of magecraft he did not specialize in.

The second was that the boy had a total of at least 70 high-quality magic circuits. This meant that Shirou was previously a son in a magus family and a very powerful one at that. But this made absolutely no sense to the Magus Killer who had researched and scouted the entirety of Fuyuki for any potential dangers during the Holy Grail War. This meant that there were two possibilities. The first is that the family of Magi recently moved to fuyuki or that the boy's family was already based in Fuyuki. The latter was the only logical possibility mainly due to the Shirous Japanese appearance and the fact that no Magi family with a right mind would move to Fuyuki when the Holy Grail War was going on.

However, it was the third thing about the boy that surprised him the most. Kiritsugu Emiya knew that if the boy was in a previous magi family then he most definitely had a magic crest. That's when he saw something glow on the boy's back. It was a magic circle and in the middle was a sword that stretched from the boy's shoulder all the way down to his tailbone. After a few moments of gaping the former mercenary took a deep breath and decided to analyze it and see what he was actually dealing with. That was when his mind was bombarded with a series of information about the crest.

Somehow the creator of the magic crest made it so that when someone analyzes the crest, the person analyzing it would receive information regarding the goal of the original ancestor. It would also seem that someone had placed a defense mechanism that would kill anyone who intended to harm the current holder of the crest. The former assassin had no intentions to do so, so instead he was seen as a caretaker and given the necessary knowledge to pass down to the crest possessor.

After he had received all the information the crest provided, he decided that it would be impossible for him to get Shirou to abandon magecraft. Not only would it dishonor his ancestors' wishes but it would leave the boy vulnerable to potential magi that want to experiment on him for their research. It was mostly because of the latter, due to him not really caring about a magi's pride.

It was also at this time that Shirou got up and his eyes started to glow a deep crimson red.

"I must say that your past is very intriguing," The boy known as Shirou said in a demonic tone.

Although he was not a traditional magus, Kritsugu knew that the being that was in front of him was most definitely not his son, at least not in the psychological sense. "Who are you and what have you done to my son?" He said in a tone that guaranteed pain of the highest amount if the entity intended to hurt his salvation.

"Relax yourself boy I have not come to harm my descendant nor have I come to harm you. It is quite the opposite really. As for who I am it is not really important but if you must know I am Sengo Muramasa, the demonic blacksmith. And believe it or not, I can help restore your family" The entity said while slowly producing a smirk that promised satisfaction beyond all else.

Kritsugu was shocked and intrigued by his answer which is why he decided that he would allow the being known as Sengo Muramasa to continue with what he wanted to say. "What do you mean by restoring my family?" he asked.

"What if I told you I could bring back Irisviel and rescue Illyasviel for you," The entity said.

"Don't speak such nonsense to me!" he shouted. " Irisviel is dead and for what reason would you have to save my daughter?" Kritsugu was furious that this being would even dare to speak of the women he loved and try to give him false hope.

"Please calm yourself. I didn't mean to dishonor the dead, I merely wish to tell you that I may be able to help you. If you will allow me, I will explain how I can accomplish things that you believe are impossible for me to achieve." After seeing that the assassin was willing to listen, the being known who possessed Shirou continued. "In the past, I negotiated with a being known as Alaya. It wanted me to be one of its counter guardians, which is the equivalent of being a slave to it. However, it did not know that I possessed prior knowledge of such things so I used it to my advantage. In exchange for my services, I asked that I would be granted one wish that would guarantee creation of any one thing I wish. This wish is still up for negotiation and I can use it to do anything I wish."

Kritsugu was speechless because he had no idea how to react to such a thing. After a few minutes of looking into the being eyes he decided to ask a question that would either break or make this deal possible.

"What do you want in exchange," Kritsugu was no fool, he knew that no one, past or present, would ever help another unless there was something in it for themselves.

"I'm surprised that you were able to figure out that I want something but I guess that is an ability you acquired throughout your career as an assassin, as well as common sense. Indeed you are correct. I require you to do something in exchange for this and that is to make sure the boy is taught how to use his… magecraft properly in order to fulfill the goal his ancestors could not."

"I- Is that all you want?" The former assassin replied in a tone of utter confusion. "For such a simple request you would waste your wish that could grant the goal that your line of descendant have tried to achieve through generations of work"

"I would not be calling bringing back your wife and rescuing your child a waste if I were you. Instead, I would call it an investment" he said, with a grin starting to form.

"An investment?"

"Yes, an investment. I will allow the young boy whose body I am currently bound to, to accomplish the goal the ones before him could not. He has gained the magic crest that has been developed through generations of hard work by his ancestors, as well as myself, therefore he should have all the necessary 'equipment to forge the weapons that the ones before him could not. Also if I were to simply wish to obtain the very thing that would do what I desired,..." he paused for a second, as if he was appreciating something and then continued "then I would feel like I have completely cheated my descendants who have put their sweat and blood through hard work into making the crest into what it is now."

He saw the confusion in the Magus Killer eyes and continued.

"You see Kiritsugu Emiya, in the past, I had considered wishing for that blade in order to accomplish my goals, however when I saw my descendant put their sweat as well as their very blood into making progress I could not. That is because I developed something called pride and that very pride would be absolutely tarnished if I were to simply wish for my goal to be complete. No, it will not be a wish that accomplishes my goal, It will be this very boy through the hard work of his past descendants!" Sengo Muramasa said while looking straight into the former assassin's eye with pride and determination of his descendants' hard work.

The assassin didn't know what to think. Kritsugu thought after the holy grail war nothing could surprise him anymore but he couldn't have been more wrong. In a single day, he received so many surprises that he was scared that he might have a heart attack. After realizing the entity known as Muramasa had no intention of granting his own wish, Kritsugu knew exactly what to do.

With a deep breath he said, "Very well then I hereby accept the terms of our agreement regarding all the participants and if you want I will even sign a Self-Geis Scroll to guarantee that the terms will be accomplished no matter what" in a serious tone, while also being one of thankfulness as well.

"The Self-Geis Scroll will be unnecessary Kritsugu Emiya, your word is enough and as for the rescuing of your daughter please leave that to my descendant. As long as you can teach him how to properly use his magic crest then he should be more than enough to rescue your daughter, I assure you," he said with confidence.

"If that is all you want then so be it, you have my word that I will train Shirou in the art of magecraft and try to make it so that he can achieve your goal as well as save my Illya. Thank you for all the kindness you've shown me" Kritsugu said with all the gratitude he could muster while muttering the last line under his breath. He then proceeded to bow in appreciation.

Sengo Muramasa could not help but crack a smile when he saw the man bowing in front of him. "Then rejoice man for your wish shall be granted!" The entity said while grinning ear to ear. " Alaya Grant the following wish of creation: I wish for you to create me the human dead boy of Irisviel Von Einzbern, specifically immediately after she was killed by the being known as Kirei Kotomine," He saw the confusion of the man he had just promised the two things he valued the most of. To which he put his hand up to stop the Magus Killer from questioning him. " I will explain everything later, for now, you will have to trust me, '' he said while putting up an apologetic smile.

"What do you me-" Kritsigu was unable to finish his question when he looked at the ground beside him and saw the resting body of his wife. He immediately went to check on her but was stopped by a wall of swords. Wait is that 'Projection magecraft' he thought. "No, it's not". It looked similar to projection magecraft but it was most certainly something different. He then looked at the being who had possessed his son.

"Allow me to finish my end of the deal and then you can check her condition" The Magus Killer simply nodded, not wanting to get on the wrong side of the being that would be promising salvation to him. The swords in front of him then had proceeded to dissipate into shiny blue sparks.

"Now then, what sword will allow me to accomplish what I wish to do," the blacksmith thought out loud while putting a finger on his chin. "Oh that's right, we can use that sword," He then proceeded to look at Kiritsugu. "and also you should also pay close attention to Magus Killer so that you can explain to the boy. I am only going to say this out loud this one time, all other times it should be done in secrecy. I hope that you can understand this."

Kritsugu simply nodded in understanding, due to being a mage himself Kiritsugu understood the secrecy of magecraft and understood why it would be bad if someone other than the creator has access to it. As well as the concept of mystery itself.

Once he was satisfied with the man's nod the old blacksmith started speaking. "Forge on"

"Forging the concept of creation

Forging the basic structure

Forging the composition material

Forging the skill of its making

Forging with the experience of its growth

Forging the accumulated years

Forging every manufacturing process"

After the entity had stopped speaking a sword had appeared in the hands of Sengo Muramasa and when it had. he had a smile of pride. And then he did it.

Light started to shine as the boy started reciting a passage that was lost to all but him and all those that came before him. "Oh great conquer of the dead give back which was not supposed to be taken. Shine like the very moon itself: Heavenly Fang Of Rebirth, Tenseiga!" The possessed boy roared the name of the blade, all the while swinging it at the corpse of the Einzbern as if it was his last action he would take in life and as he did a light passed blinding everyone near him. This of course included the Magus Killer.

After a few moments the light disappeared, Kritsugu slowly opened his eyes and for a minute he had no idea what he was doing outside. That was when all of a sudden a rush of thoughts came to his head and he had one of the worst headaches one could ever imagine

(Try Imagining a headache, FYI It hurts a lot)

After regaining his bearings over his thoughts Kritsugu looked towards the dead body of his wife and what he saw enraged him. His wife was still on the ground, eyes closed, and looked to be much of a corpse as any other corpse would be. Just as he was about to start yelling at the being who had promised things beyond his comprehension, a cough had stopped him in his tracks.

*cough* *cough*

He took his eyes off from his possessed son and looked in the direction of his dead wife. Or not dead wife because while looking in her direction her crimson red eyes slowly opened and all his hope was restored when she said the following words.

"Kiritsugu is that you my husband," she said while having a smile that was in the middle of surprise and that of happiness.

But before he could answer her the possessed boy interfered by stepping in his path. The boy looked into his eyes and said the following words.

"That sword I used can only bring back a person once from the dead, never again and I should also tell you that your life has also been restored."

The Magus Killer cocked an eyebrow at this, as he himself was not dead.

"I am not sure how but It would seem that the sword thought you were dead and as result, that curse you were infected with was purified. This however means you also will be killed for good the next time you die. However, this is not why I prevented you from reuniting with your beloved. Instead, it is because my time is up and I need to go to Alaya to see how this negotiation ends now that it has fulfilled its part of the bargain I will have to fulfill mine, in other words, become her slave. This means I leave the rest to you Mr. Emiya, I hope you don't disappoint me and keep to your word. Farewell, and I wish you the best of luck" As he said this the boy closed his eyes and was about to fall but before he could reach the ground Kritsugu had caught him.

"Don't worry I will not break my word to you Sengo Muramasa, for you have given me something no one in the world has and that is a chance to make things right" He whispered while carrying the boy in the direction of his mother and his wife.

Thank You to those that ended up reading my story. As you may be able to tell this is my first story ever. Any sort of criticism or feedback will be appreciated.

All hail KingsManEmperor totally not me but I do here he is awsome.