The Holy Grail War.
A battle where seven Masters and seven Servants vie for supremacy to obtain the omnipotent wish-granting device. A slaughter where heroes from all eras and all nations are revived in the modern age to compete in strength. The victor claims ownership of the Grail. The last one standing becomes the Master of the Grail.
Saber, Archer, Lancer, Rider, Caster, Assassin, Berserker.
The Holy Grail War of 2004.
However, it was slowly proceeding much earlier than that.
Here, there is a child abandoned by her parents. No, the girl who was once a child had grown into an adult over time. Although she still bore the appearance of a child, she was an 18-year-old girl, soon to be an adult.
The Lesser Grail, chosen as the Master of the Einzberns, one of the Founding Families that created the Holy Grail.
Illyasviel von Einzbern.
Possessing an innate and immense amount of magical energy, she sought to get ahead of the other factions by summoning her Servant early, even though it was a time when she couldn't yet receive support from the Greater Grail.
With her mother dead and abandoned by her father, the girl grew into a cold-blooded person, treating even her closest aides coldly. Her purpose in summoning a Servant this time was strongly inclined towards using them not as a person, but as a tool.
Two months before the Holy Grail War, she summoned Berserker at the Einzbern Castle.
"——Come from the Ring of Deterrence, Guardian of the Scales!"
Paaaaaa!!!
A strong light surged from the summoning circle drawn in blood, filling the room. Soon, the light faded, revealing a blue-haired boy standing atop the circle.
"Servant Berserker. Fergus mac Róich. I have answered your summons."
"...The King of Erin is a child...?"
Though he was taller than Illya herself, he was a boy with a slightly smaller build than her maids, Sella and Leysritt. No matter how you looked at it, he didn't feel like an adult.
"Isn't it normal for ancient people to be short? Though everyone around me was unusually large. Before the Industrial Revolution, a human height of 160cm was considered tall, you know? I am small compared to warriors, but I was slightly taller than average in Erin..."
It was true. In reality, the average human height increased starting from the Industrial Revolution. While the average height of skeletons from 14,000 years ago was in the 170s, by 3000 BC, it was barely 160cm at best. Fergus was actually around average height. It was just that the warriors around him, including Cú Chulainn, were huge; most men were in the 150s like him or even smaller.
"Ah, I see... No, wait, are you really a Berserker!? Are you really Fergus mac Róich!?"
"Yes, I am. Shall I show you Caladbolg?"
"...Different from what I imagined."
Illya had deliberated between two catalysts: a cornerstone from the Temple of Heracles and a fragment of the throne from Ulster Castle. Between Heracles, who had a history of going mad and rampaging, and the Celtic hero Fergus—specifically the most famous King of Ulster—she chose Fergus. The summoning was a success, but the visual was unbelievable.
There were records of Fergus being a bishounen (beautiful boy), but because he was such a deified hero in Ireland, many versions described him as a macho man fitting the era's ideal. So Illya had expected a visual similar to Heracles.
However, here was a small boy with only lean muscles. Thinking she drew a dud, Illya was disappointed...
"....What are these parameters!?"
Strength EX | Endurance EX | Agility EX | Mana E | Luck A | Noble Phantasm EX
Unprecedented, enormous parameters. It was truly the pinnacle of brute strength. Fergus had spent his entire life building his strength, never neglecting a single day. As a result, in terms of raw power, he was the greatest human in Celtic history, and Mad Enhancement further boosted his parameters. While his parameters in life would mostly stop at A+, his deification allowed his parameters as a Heroic Spirit to ascend even higher.
Of course, Fergus himself was a warrior who emphasized technique as much as strength.
"And what are these Skills and Noble Phantasms..."
Eye of the Mind (True) A+, Fair Youth of the Slitted Eyes A, Bravery A+, Battle Continuation A, Charisma of Ulster A+, Beast Slayer A, God Slayer A, Wisdom of Dún Scáith A+, Primordial Runes, Forged Constitution EX. And his Noble Phantasm was at least A-rank. It was like winning the lottery jackpot.
Fergus, often evaluated as the Celtic version of Heracles, was absurd even as a Heroic Spirit. However, he was a Servant that consumed a massive amount of magical energy. If the Master of the 4th War's Berserker (Kariya) had summoned him, he would have likely died from shock instantly upon summoning.
"Illya, Berserker is handsome."
"Leysritt! What are you saying all of a sudden! Certainly, he is handsome, but..."
"Fair Youth of the Slitted Eyes... What is this skill?"
"Haha, it's a charm (fascination) skill. Well, unless I use it, it doesn't activate normally."
"...I see."
Illya nodded, impressed by the level befitting a King of Erin. Moreover, despite being a Berserker, communication was unexpectedly smooth. It couldn't be better. And then...
"Master, shall we start with your story?"
"What? What story."
"Your story. Illyasviel von Einzbern... Sadness and hatred from being abandoned by your family... You are filled with love-hate!"
"! H-how do you know that..."
"I possess the Wisdom of Dún Scáith. It is a power that touches the Root."
"The... Root...?"
Knowing that the Einzbern Grail is a miracle of the Third Magic that touches the Root, Illya couldn't help but be shocked by Fergus casually mentioning touching the Root. Fergus carved runes into the air, instantly creating a chair, and sat down. Then, he immediately lifted Illya and sat her on his lap.
"Wh-what are you doing!?"
"I can resist even Command Spells~ So, let's talk. Seeing you reminds me of my children. The children I had to leave behind to sever ties with the gods... You resemble Connla."
"Connla... You mean the Connla who became a general of Ulster after your death?"
"You know well? It wasn't after my death, but I'm happy you know~ Oops, I almost started bragging about my kids. Illya... I am a King, but also a father of a family. So, could you tell me your story? I want to help you."
"...Since you don't seem like you'll let me go, fine. Sella, Leysritt. Leave us."
After sending her maids away, Illya glared at Fergus. Fergus just grinned slyly at her.
Illya slowly began to tell her past. At first, her mindset was just to give a rough summary and end it... but seeing Fergus listening seriously and sincerely, the sense of betrayal, sadness, and grief she had felt in the past began to flow out. She vented her hidden emotions, pouring out her story and her pain.
"It must have been painful. It must have been sad. It must have been hard... You had no choice but to endure all that pain alone in this castle."
"Hic... Hic... Uuung..."
"It's okay now. Because I am here."
"Fergus..."
"Leave it to me. I will definitely win this Holy Grail War for you. And... I will give you hope."
This was the beginning of a new story.