In a certain mansion located in Fuyuki City, Japan. Although it was a mansion with a basement and two floors, only one 16-year-old girl lived there.
She was Tohsaka Rin, the 6th head of the Tohsaka family.
Tohsaka Rin, an honor student in her second year of high school, the same grade as 17-year-old students due to being born early in the year. Her family was originally a martial arts household, but about 200 years ago, starting with the first head, Tohsaka Nagato, it became a magus lineage specializing in Jewel Magecraft. Perhaps because their roots were in martial arts, she was someone who had learned Chinese martial arts from her legal guardian, Kotomine Kirei.
Using Jewel Magecraft and being highly talented, she was also fairly confident in close-quarters combat.
Such a girl had come to the basement to participate in the Holy Grail War, the long-held wish of her family and the war in which her predecessor, her father, had fought and died.
"I wasn't going to use a catalyst... but still, since Father gave it to me."
She had brought one item with her. It was an old stone that seemed to have some kind of characters carved into it, now faintly visible. They were runes. Though it no longer retained any magical ability and was merely a relic, its value as a catalyst was immense.
In the past, her predecessor, Tohsaka Tokiomi, had prepared two catalysts. A snake skin and a rune stone. After pondering which to use, he used the snake skin and gave the remaining rune stone to his daughter, Rin, as a memento.
Since she had no particular Servant in mind anyway, and knowing the remaining classes were Saber and Archer, Rin, thinking the rune stone would naturally summon a Norse-related figure, a user of runes like the legendary Sigurd, prepared to summon a Saber.
She made her summoning preparations at 2 AM, her peak condition time... but in reality, it was 1 AM, as all the clocks in the house were, for some reason, running an hour fast. She knew this but had forgotten, and proceeded with the summoning.
"Fill, fill, fill, fill, fill. Repeat five times for each. Simply, shatter the filled time. The base is silver and iron. The foundation is stone and the Archduke of Contracts. Our ancestor is my great master Schweinorg. A wall to block the falling wind. The gates in the four directions close, coming from the crown, let the three-forked road from the crown lead to the kingdom."
Rin reached her hand toward the glowing summoning circle, reciting the summoning chant to bring a hero to her family. Soon, the circle reacted and began to shine.
"I announce. Your body shall serve under me. My fate shall be with your sword. Submit to the beckoning of the Holy Grail. If you will submit to this will and this reason… then answer! An oath shall be sworn here! I shall attain all virtues of all of Heaven! I shall have dominion over all evils of all of Hell! You, seven heavens, clad in three great words of power..."
The summoning circle, which had been shining with a green light, soon glowed with a red light.
"Come forth from the ring of restraint, guardian of the scales!!!"
*Fwoooosh!!!*
A red light filled the room, and a small amount of smoke rose.
"It's done... it's a success!"
Rin, sitting down from the strong magical reaction, looked at the Command Spell engraved on the back of her hand and cheered for her success. However, there was no one around. With a dumbfounded look, she kept looking around, bewildered.
"What the...?"
*Thud...!!!*
Just then, a loud noise echoed from above, followed by the sound of something breaking.
"Wh-what was that!?"
She went up to the floor directly above, tried to open the door to where the sound came from, but it seemed broken and wouldn't open, so Rin forced it open and entered. Among the disheveled furniture, a boy was lying on the floor.
"My my, this is truly a troublesome summoning..."
".... Huh?"
The boy got up, brushing dust off his head. The standing boy was a petite, blue-haired youth who looked slightly shorter than Rin. A boy with noticeably narrowed eyes. Rin thought his jade-like skin looked like it would be soft to the touch. Unbeknownst to her, her heart was already pounding.
"Are you my Master?"
"Uh....? Uh, uhh... yes."
"Pleased to meet you. I am Fergus, Fergus mac Róich. I have manifested as an Archer, a warrior of Ulster."
"Fergus... mac Róich? That great hero of Celtic mythology...? No no, more importantly, an Archer!?"
Rin stared at him blankly, then was surprised that it was Fergus, and doubly surprised that he had come out as an Archer.
"An Archer, an Archer!? ... Ah, our house clocks are an hour fast.. I messed up!"
"Are you disappointed that I'm an Archer? Well, compared to my original self I have weakened, but I don't see any particular problem?"
"No problem? ... What are these parameters!?"
Strength A, Endurance A, Agility A++, Mana E, Luck A, Noble Phantasm A.
They were unbelievably, overwhelmingly strong parameters.
"This is amazing!? Aren't you stronger than Saber, who's said to be the strongest!?"
"Well, perhaps? However, I don't have Caladbolg, my strongest weapon. I do have Cruaidín though."
"Eh... but, in the myths, you used Cruaidín more, right?"
"You know well? I'm glad~ I thought you might not know since Celtic mythology is rather niche. Caladbolg was too powerful and hindered my growth, you see. So I favored Cruaidín. That's why I always come with Cruaidín, no matter the class. Its form can change freely."
Looking at his parameters, terrifying skills, and Noble Phantasm, Rin felt reassured even if he wasn't a Saber. Still, it was a bit disappointing that he lacked Caladbolg, called the original of holy and demonic swords.
"But, who would have thought that Fergus would be such a pretty boy..."
"Haha! Even if tales are passed down, most don't believe them, and many versions depict me as a rugged macho man, right? That's how things get distorted or changed as time goes on. Well, in Greece, guys like Orion or Heracles were pretty boys too. Feminine men were also popular... Ulster had some of that to an extent as well. Perhaps it's a characteristic of the Age of Gods?"
"That's a scary era in a different way. Certainly, despite your appearance, I can feel tremendous magical power. With this, you're undoubtedly the strongest! Then Archer, I'll give you your first mission!"
"Yes, what is it?"
"Clean up this place!"
"... Ah, yes."
As if thinking 'Is that all...?' he tilted his head, then drew a primordial rune in the air. Using a rune of restoration, the furniture tidied itself as if time were flowing backwards. It wasn't time reversal, but a form of magecraft that restored objects to their previous state.
"Ooh... this is, the Primordial Runes. The magecraft of the gods..."
"I can't teach you rune magecraft. I'm not good at teaching magecraft. But I can show you as much as you like?"
"I see. That's amazing... Ah, there are plenty of empty rooms in the house, so rest anywhere. I'm sleepy, so I'm going to bed..."
Tired from summoning a Servant, Rin left the room first, leaving Fergus in the living room. He looked around the room once, then opened the window. And he threw the rune stone out the window. Watching the rune stone emit a small light and then crawl along the ground, quickly disappearing somewhere, Fergus grinned, leaned against the window, and muttered to himself.
"Try saving her this time, Setanta. A gift for you, the oblivious one. This time, let's fight properly as warriors. Together with your Master, the descendant of the Knights of the Red Branch..."
Closing the window, Fergus gazed vaguely into the air.
"Conall... your descendant has grown so strong. If I were summoned as a king, I probably wouldn't bother saving anyone besides my Master... but since I've manifested as a warrior, I'll help. I'll see for myself if the Gáe of Ulster is still intact."
With a pleased smile, Fergus left the room and began cleaning the house.
Time passed, and morning came...
Rin woke up after 9 o'clock. It was already too late to go to school. So she decided not to go at all and, thinking she'd show Fergus around Fuyuki today, left her room.
Leaving her room and coming down to the first floor, she saw Fergus in the kitchen preparing breakfast. He was wearing casual clothes that looked different from when he was summoned.
"You're awake, Master? I tried preparing breakfast, is it alright?"
"Uh... uhh. Thanks."
The breakfast Fergus prepared was simple Japanese curry. And it was incredibly delicious. To a level hard to believe was made by a mythical king.
"It's delicious..."
"I'm glad you enjoy it~ If you wish, I'll take care of breakfast every day."
"Every day, breakfast...?"
"... That might be nice too."
It absolutely couldn't be personal feelings. Probably, it wasn't.
"Ahem... I'm not going to school today, I was thinking of showing you around Fuyuki. Is that okay?"
"If that's what Master wishes~ But, before that, may I know your name?"
"My name? Ah, I forgot yesterday because I was tired. I'm Rin, Tohsaka Rin."
"I see. Then, nice to meet you, Rin."
"Nice to meet you too, Archer."