Strength Magic.
One of the magic skills Emiya Shirou learned from a young age. Because his father, Emiya Kiritsugu, was once a Caster, he taught Shirou some basic magic techniques.
But because Shirou didn't seem to have any particularly outstanding magical talent, he was only able to use the most basic magic: strength magic.
The so-called strength magic is about understanding the material and structure of an object and injecting magic power to enhance it for a short time.
It can be used not only on external objects, but also on the human body, and even directly on a single organ, to strengthen it in a conceptual way.
As a type of magic that's easy to start with, but very difficult to master, Shirou had a very low success rate when he first started learning strength magic. He often failed, causing damage to the strengthened object. Therefore, he rarely strengthened his own body, and mostly worked on external objects.
In his various attempts, he found that his success rate for strengthening weapons, especially swords, was quite high, far better than strengthening other items. So, his subsequent strength magic practice was basically only focused on weapons.
However, even the almost-adult Emiya Shirou couldn't have split such a large rock in half directly with weapons strengthened by strength magic.
There could only be one reason for all of this: the influence of Servant Emiya on him.
Because on that snowy night, Shirou used a blank Servant card to summon himself from a parallel world, he merged with Servant Emiya and killed all the other Servants created by cards overnight, winning the Holy Grail War.
In that battle, his existence was so close to being in sync with Servant Emiya that his soul merged with Servant Emiya's soul.
This caused him to retain Servant Emiya's power, even Servant Emiya's entirety, in his body even after losing the card!
"I am the bone of my sword!"
This incantation, which originally belonged to Servant Emiya, now spoken from Emiya Shirou's mouth, was equally powerful, leading to an unimaginable boost in his strength magic.
It's just a pity that his current child's body doesn't have enough total magic power to allow him to recite the rest of the incantation.
Otherwise, he might be able to directly recite the entire incantation and once again show the skill he used in the battle with Angelica, who used the Gilgamesh card, the Unlimited Blade Works.
Memories of the past flooded Shirou's mind, causing fluctuations. The Greyrat family, alerted by the loud noise in the yard, rushed over.
"What happened!"
The first to arrive was Paul. He thought there had been a monster attack, so he specifically put on his armor and equipped his weapons.
However, when he saw the rock split in two in the yard, he couldn't help but gape in surprise.
"Huh... What... What happened here... Shirou, are you okay?" Although surprised by the destruction of the rock, Paul was more worried about Shirou's safety. Then he looked around suspiciously, muttering to himself, "Is it a monster? Did a monster do this? But there's no monster nest near here?"
"Oh dear..."
Next, Zenith arrived, carrying Rudeus.
She was much calmer than her husband. After observing the environment and finding only Shirou and the large, split rock in the yard, she muttered to herself, "Could it be... Did you do this, Shirou?"
"Sort of."
Knowing that he couldn't hide it, Shirou didn't have any intention of concealing his strength.
Although magic and his past were secrets he couldn't reveal, Shirou didn't need to hide anything else from the Greyrat family.
"Huh? Did you do it, Shirou?!"
Paul heard Shirou's words and belatedly looked over.
He had actually suspected Shirou of doing it, but because he couldn't accept that a child could do such an exaggerated thing, he had been trying to deny the possibility and look for other clues.
But now, the reality that Shirou admitted forced him to admit that it was all done by this boy who looked no more than seven years old.
"Shirou, did you really do this?" Paul seemed a little unwilling and asked again as if to confirm.
"Yeah, didn't you tell me to practice swordsmanship with the goal of cutting this rock in half? You also said that only by doing this would I be qualified to receive real training." Shirou said calmly, "Now I've done it. Can you officially teach me swordsmanship now?"
"Uh..."
Paul never expected that his careless words from back then would actually be taken to heart by this boy, and that he would actually accomplish it.
He blankly recalled his own childhood, remembering that when he was seven years old, he was still playing in the dirt at home and never even thought about knight training.
For a moment, the strong sense of contrast even made Paul feel regretful, regretting that he hadn't been more serious back then, and now he was being surpassed by a child.
Regret, jealousy, embarrassment, bitterness, and other complex emotions gathered in his heart, causing this middle-aged knight, who was now a father, to even feel the urgency of his youth.
"Honey, don't think too much." Zenith saw Paul's emotions and comforted him, "Shirou is our child, after all. Shouldn't we be happy that our child has outstanding talent?"
"No, but I said... To be able to cut such a large rock in half with one sword, you'd have to be at least a mid-level Swordsman..."
"Intermediate Rank Swordsman? Wow, Shirou, you're amazing! As expected, our child is a genius!"
Zenith's shout drowned out Paul's words.
She hugged Shirou's shoulders and jumped up and down happily, looking more like an ordinary young girl than a wife.
This couple definitely has issues...
Shirou thought to himself.
At the same time, besides Paul and Zenith, Shirou also noticed Rudeus's gaze.
Although he tried to be subtle and didn't make any eye-catching movements, Shirou still noticed that Rudeus was staring seriously at the rock he had cut in half, with a certain unwillingness or strong desire to compete in his eyes.
Although this desire to compete was only fleeting and was quickly replaced by an increasingly strong sense of awe, it still didn't escape Shirou's notice.
"Without further ado, Paul, hurry up and teach Shirou swordsmanship!"
"No, I said, honey... Shirou is only seven years old this year. Isn't it too early?"
"What? He's already able to do what a Intermediate Rank Swordsman can do. Shouldn't we hurry up and teach him more swordsmanship? Maybe our family can produce a Sword King!"
"Sword King... I'm only an upper-level swordsman, not even a Sword Saint yet, and my son is already aiming to be a Sword King?"
"Hehe, that just means you're not a good enough dad."
"Damn it! From today on, I'm going to double my original training time! Shirou, I definitely won't lose to you, aaaaah!!!"
Shirou couldn't help but show a helpless expression when he saw that Paul, an adult, was competing with him, a child.
He might have to take care of Paul's feelings in the future and not let him suffer too much of a blow.