"Is that the legendary one? The cup filled with the blood of gods, capable of performing all kinds of miracles, even granting the world itself. But isn't that just a myth?"
Shinji nodded, "Yes, although it's not exactly like the legend, there is an underground leyline in this city where a ritual similar to the legendary Holy Grail can be performed. This is known as the Holy Grail system. It's said that the person who obtains the Grail can have any wish fulfilled. The war you've been dragged into is a battle to complete the Holy Grail ritual and seize the final Grail—the Holy Grail War."
Shinji then briefly explained to Shirou about the Holy Grail War, what Servants and Masters are, the nature of Heroic Spirits, their relationships, and the command seals that bind Servants, as well as their role as sources of mana or powerful spells.
Shirou nodded thoughtfully, "I see. So the Holy Grail pre-selects seven magi, marked by these holy marks on our hands, and these chosen magi must summon Heroic Spirits like Saber to be their Servants. Once all seven pairs are ready, the Holy Grail War begins."
"That's right."
"But Shinji, I still don't get it. If the Holy Grail is such a wonderful thing, why must we fight to the death for it? Can't everyone just share it?"
"You'll have to ask the overseer of the Holy Grail War that question later. I have to go there soon anyway. Being a witness to this war and almost getting silenced, he's the only one who can help me now."
"Overseer?"
"Yes, someone who knows the detailed rules. All I can tell you now is to always be prepared for battle, be ready to kill or be killed, and never use up your command seals unless absolutely necessary! If you run out, you will die!"
"But didn't you just say that we only need to deal with the Servants? Why do I also have to..."
"In theory, yes, but as a magus, can you really defeat your own Servant?" Before Shirou could answer, Shinji continued, "No, right? So the simplest way to eliminate other Servants is to target their Masters. Does it make sense now?"
"Yes." Shirou wasn't stupid; he quickly understood the implications with Shinji's brief explanation.
"No, wait!" Shirou suddenly thought of something, "Shinji, how do you know so much? Are you a Master too?"
"No, just an informed person. Although our family was once a historic magic family and even participated in the past four Holy Grail Wars, we withdrew from the world of magic after my grandfather's death. But this withdrawal is a recent development."
"A magic family, huh?" Shirou was surprised and a bit sentimental, but his curiosity soon took over, "Why did you withdraw from magic?"
"There are several reasons. Firstly, our family migrated here from another country, and Japan's ley lines don't suit us, so over time, our magical abilities dwindled. By my generation, I don't even have the basic prerequisite for being a magus, a magic circuit, signaling the end of the Matou family's magic lineage.
Secondly, it's happier to live as ordinary people, both Sakura and I think so. There's a third reason too, but it's not really important.
So, after my grandfather passed away, I officially led the Matou family out of the world of magic. From then on, the Matou family had nothing to do with magic or mysteries."
"I see. I didn't expect your family to have such a history, and to have participated in four Holy Grail Wars. That's quite surprising."
While performing fire therapy on a rabbit, Shinji casually replied, "Well, others might see me as an unfilial descendant who ended the Matou family's centuries-old obsession."
"It's not your fault, Shinji. Without magic circuits, it's not something you could control." Shirou defended Shinji, but then he suddenly noticed something, "Wait, Shinji, what are you cooking?"
"Braised rabbit."
"So, you turned that rabbit into a dish?! Wasn't that your life-saving rabbit?!"
"Saving lives till the end, delivering kindness all the way. It saved my life, and in the end, it used its body to save me from hunger. It's truly a noble creature."
Seeing Shinji's look of sentiment, Shirou's mouth twitched again.
"You really are..."
"Don't worry, with such great merit, this rabbit will surely be reborn as a human in its next life. Bless it."
"If Issei knew, he would definitely pull out the ruler."
"Can I call you Saber?"
At the low table, Shirou scratched his cheek, feeling a bit embarrassed to look Saber in the eye, "What Shinji just said..."
Saber, sitting at the low table, nodded affirmatively, "Yes, your friend is correct. Only the last pair of Master and Servant has the right to obtain the Holy Grail."
Shirou didn't respond, instead, he tightly grasped one arm. Thinking about how such meaningless slaughter had already occurred five times in this city made his heart tighten. He asked, "Shinji, did anyone obtain the true Holy Grail in the previous four wars?"
"The first three wars happened too long ago, I only know they all failed and no one obtained the Grail. As for the last war, which was ten years ago, my uncle represented the Matou family but failed midway. However, I heard someone won and obtained the Grail."
"Did they make a wish?" Shirou asked, frowning.
"How could I know?" Shinji shrugged, "If you want to know more about the command seals, I can tell you, but other things..."
"Does the Matou family know a lot about command seals? You mentioned several uses earlier."
"Of course, the command seal system was developed by the Matou family."
"What?!" Shirou was shocked.
"Although it's fine to tell you now, it's better to hear it from the overseer than from me."
"I'd rather hear it from a friend."
Shinji sighed softly and continued, "In short, you need to know that Fuyuki's Holy Grail system was created over two centuries ago by the combined efforts of three magic families. The Matou family contributed the command seal system that controls Servants, while the other two families provided the ley lines of Fuyuki and their family secrets.
Because of this, our three families were once called the rightful owners of the Holy Grail, known as the Three Great Families. Unable to achieve their respective goals alone, they chose to cooperate and built the Holy Grail system on this land's ley lines.
However, since there is only one Holy Grail and all three families wanted to monopolize its results, they tore up the agreement and became enemies at the start of the first Holy Grail War.
Due to the failure of subsequent Grail summonings, the current Grail doesn't belong to any family. The Three Great Families are now just participants in the Holy Grail War without any special privileges, only having the non-privileged privilege of being easily chosen as Masters by the Grail."