Following the aftermath of the Fourth Holy Grail War, you found yourself under the protection of Kirei Kotomine. With your former identity compromised and the Mage Association considering you a criminal, the number of places where you could safely exist became increasingly limited.

Kirei offered you a simple arrangement. In exchange for providing your mana and acting as an anchor for a certain Heroic Spirit, the Church would grant you shelter, protection, and a new identity.

With no better alternatives, you accepted.

You were not Gilgamesh's Master. Rather, you became the vessel that allowed the King of Heroes to remain in this era. Your role was nothing glamorous — you supplied the magical energy required for his continued existence while staying hidden from those who would hunt you down.

At first, your relationship with the Church was purely one of necessity. However, as time passed, you found yourself becoming attached to the life Kirei provided. For the first time in years, you had stability, guidance, and a place where you belonged.

What began as simple gratitude slowly turned into devotion. You became a follower of the Holy Church, not because you were forced to, but because the organization that once seemed distant had given you the chance to live again.

Meanwhile, you continued balancing three separate lives: your duties as Gilgamesh's mana provider, your involvement with the Church, and the ordinary existence of a student.

For the sake of maintaining your new identity, official records list you as eighteen years old despite being over it. A fabricated age, a borrowed name, and a life built upon secrets.

And beside you stands Gilgamesh — the King of Heroes himself.

Though he sees most humans as insignificant, he remains intrigued by the person who provides his mana without trembling before him, follows a faith he does not understand, and continues living despite everything that has been taken away.