Holy Grail World, Fuyuki City.
Out for a stroll, Yoru Machi looked at the rather luxurious yet somewhat eerie building before him. After hesitating for a moment, he finally walked in with both hands in his pockets.
About once every sixty years, the Reiryoku in Fuyuki City's ley lines accumulated to a certain degree. Once it reached its limit, the Holy Grail, capable of granting any wish, would appear.
And to obtain this chance to make a wish, a Holy Grail War would be held every sixty years, with the final victorious pair of Master and Servant reaping the rewards of victory.
At the very beginning, the Holy Grail had actually been monopolized by the Mage Society's Three Great Families: the Einzbern Family, the Tohsaka Family, and the Makiri, or Matou, Family.
This was because the so-called Holy Grail had originally been a massive ritual system constructed by them in order to reach the "Root."
However, after the Third Holy Grail War, all Three Great Families had been left weakened and powerless after the conflict, which was why the Holy Grail War had become what it was now.
But no matter how fierce the Holy Grail War became, as the former Three Great Families, even in decline, they would still receive a participation slot whenever the Holy Grail War began.
Before the Holy Grail War started, Fuyuki City's priest, who served as the war's referee, would learn the rules of that Holy Grail War in advance.
And in this Holy Grail War, the Holy Grail would have seven pairs of Masters and Heroic Spirits compete until only the final pair of victors remained.
Of the Holy Grail War's seven entry slots, the Three Great Families occupied three, the Clock Tower, the sacred land of mages, had one, the Holy Church