The Holy Grail is a powerful, ancient relic capable of granting any wish the beholder desires. In order to obtain this power, various magi known as "masters" summon legendary Heroic Spirits called "servants" to fight for them in a destructive battle royale—the Holy Grail War. Only the last master-servant pair standing may claim the Grail for themselves. Yet, the third war ended inconclusively, as the Grail mysteriously disappeared following the conflict. Many years later, the magi clan Yggdmillennia announces its possession of the Holy Grail, and intends to leave the Mage's Association. In response, the Association sends 50 elite magi…