What Shinji needed to do could be summarized in one sentence—give his counterpart in this world a cheat, or rather, unlock his magic circuits.
Although technically, the Shinji from this world and the Shinji standing here were not the same individual, facing someone who looked identical, shared the same background, had the same body, and even similar experiences and thoughts—how could he truly treat the other as a stranger?
If Shinji in this world had a happy and fulfilling life without needing external intervention, Shinji would have just taken a look and quietly left. But, this world's Matou family was even more in decline than the one Shinji came from, and the Shinji here had an even stronger determination to pursue magecraft.
Seeing himself in such a state, Shinji couldn't just stand by and do nothing.
Just as Justeaze had given him an opportunity for a new future, he wanted to give himself in this world a chance to walk a different path.
Thus, the scene was set: the older Shinji helping the younger Shinji to unlock his magic circuits.
Any magus with a bit of knowledge about the mystic world would know that unlocking completely sealed magic circuits is a thankless and laborious task. It not only requires consuming a huge amount of mana—if we compare a normal magus's mana to a common vehicle engine, the mana required to unlock sealed magic circuits would be like a nuclear reactor—but also involves great risk—the output of a nuclear reactor is not something an ordinary vehicle can withstand, and any misstep could lead to catastrophic failure.
Such a tremendous cost is something even ancient magus families might not be able to bear, let alone for an uncertain future magus. It seems an endeavor not worth the investment, something only a desperate person like Justeaze would be willing to gamble on.
However, Shinji had no such concerns. The enormous mana consumption for unlocking sealed circuits is largely wasted due to the lack of understanding of the target magic circuits, necessitating repeated trials to find the correct path. But Shinji was different; his target was himself from another world with identical magic circuits. He didn't even need to think; he could instinctively find the correct path.
Moreover, since it was his magic circuits, he knew their limits well, eliminating worries about excessive output causing harm to the body or rejection issues from foreign mana, thereby maximizing efficiency.
As for the nuclear reactor level output, it was no problem for Shinji with his Servant body. A Servant's body is inherently composed of mana, and Shinji knew how to "release mana" as a skill, capable of momentarily unleashing maximum output comparable to Justeaze using the Greater Grail.
In other words, only Matou Shinji who had become a Servant could single-handedly and safely undertake the project of unlocking the magic circuits for his counterpart in another world.
While the project sounded complex in explanation, it didn't take much time in practice.
A vast amount of mana, continuously and intensely, flushed through the boy's magic circuits, breaking through the innate seals one by one, bringing immense pain to the boy. To describe it, it felt like a heavy hammer striking his body every second, causing swelling all over while keeping him consciously aware of the pain.
Surprisingly, this world's Shinji showed remarkable determination. Despite enduring such extreme pain, he merely clenched his teeth and didn't utter a sound, even though he was drenched in cold sweat and his veins bulged, even biting his lips until they bled.
"The decline of the Matou family has forged your will. Excellent. To achieve greatness, one must not only have extraordinary talent but also indomitable will. With such willpower, the future mystic world will surely have a place for you."
Shinji highly praised this perseverance. Judging by willpower alone, the boy's performance surpassed his own back in the day.
Amidst Shinji's laughter, his stored mana rapidly depleted, reducing his time in the present world from the original two days to less than half a day. But this sacrifice brought enough reward: all thirty-two magic circuits were fully unlocked.
As Shinji withdrew his hand, the boy lost consciousness simultaneously—he had already reached his limit, barely holding on, and with the pain gone, he finally let go.
Draping a coat over the boy and using the remaining mana to inscribe an "EIHWAZ" rune on his forehead, Shinji shifted his gaze from the boy to the corner connecting the courtyard and the house.
"Sleep, sleep. When you wake up, the world will be different, and so will your life—don't you think so, Zouken Matou?"
A gaunt, large-headed, small-bodied old man, resembling an alien, hobbled out of the shadows with a cane. His appearance was unforgettable, just like the Zouken Matou Shinji had killed in another world.
Zouken bowed shakily to Shinji. "Thank you, young man, for your great kindness to Shinji and the Matou family."
"Spare me the useless formalities. I did this because I find the boy pleasing, not because of you or the Matou family."
Shinji snorted coldly, his longstanding aversion to Zouken Matou ensuring he wouldn't show any kindness.
"Shinji is, after all, my grandson. As his grandfather, it's only right for me to express my gratitude."
The old man's expression remained unchanged, seemingly unbothered by Shinji's rude attitude.
"If you have any requests, please feel free to ask. The Matou family will do everything in its power to meet your demands."
Shinji narrowed his eyes, hinting at something, "Do everything in your power? When did the illustrious founder of the Three Families, the magus Makiri Zolgen, become so accommodating?"
Zouken's old face finally showed a reaction. "To be honest, young man, ever since the Greater Grail was taken, I should have died. But I couldn't let go of the declining Matou family and wanted to see what would become of the Greater Grail, so I've been clinging to life until now. Currently, I'm just an old man not much stronger than an ordinary person, as fragile as a bug before you."
Shinji expanded his perception to the fullest, locking onto the old man before him without restraint. "More than sixty years have passed, and your injuries haven't healed at all? Your insect magecraft may be lacking in other areas, but in terms of healing and prolonging life, it's world-class."
"Young man, you flatter me," Zouken responded, still unruffled, his demeanor as lowly as ever, though there was a hint of wistfulness in his words. "But as you said, my physical injuries don't concern me. My wounds are on the soul. The magus who took the Greater Grail was adept in soul magecraft and left me with irreparable damage. Since then, I've been little more than a cripple."