Fuyuki City is the setting for a secret and violent war among competing magi. For the past two centuries, seven magi were gathered and engage in a Battle Royale, each gambling his or her own life to obtain the Holy Grail, a legendary chalice capable of granting wishes. The past four Holy Grail Wars have typically occurred every sixty years, with the most recent concluding a decade ago, but the fifth war has eerily started prematurely.
Each magus, better known as Masters, are aided by one of the seven summoned spiritual familiars known as Servants, who are the reincarnations of legendary souls from all across time. These resurrected Heroic Spirits (英霊 Eirei?), possess superhuman characteristics and wield powerful artifacts or abilities called Noble Phantasms (宝具 Hōgu?). A Noble Phantasm's hidden abilities may be released by invoking its true name, but casual brandishing of a Noble Phantasm is best avoided, for symbolic Noble Phantasms usually belie a Servant's identity, diminishing that Servant's competitive advantage. Specific legends may be summoned with the aid of catalysts, which are artifacts, ideas, or experiences similar or of value to the desired Servant. Only one Servant can be summoned in each war from one of seven classes: Saber, Archer, Lancer, Berserker, Rider, Assassin, and Caster.
The Holy Grail is a spiritual artifact, so only astral entities, such as Servants, are capable of touching it; this restriction forces Master and Servant to cooperate with each other against rival pairs, even if a situation entails fighting to the death. Masters control Servants with three Command Mantra (令呪 Reiju?), which are crystallized miracles issued by the Holy Grail that manifest on a Master's hand. When activated, Command Mantra permit a Servant to accomplish an incredible feat, or alternatively provide Masters with the authority to issue an irrevocable and absolute order to a Servant. In the event of a Master's demise, a Servant may choose to bind him or herself to another Master; if a Servant is slain, a Master may ally with a wayward Servant or pursue sanctuary with the Holy Grail War's impartial supervisor, who is traditionally a delegate of the Church.
Despite the attempts to destroy the Holy Grail and stop the wars, another Holy Grail War has been set into motion. Magus from all around compete in an attempt to win the ancient artifact and grant their greatest wish. A new city has been selected, and new Magus are ready to take on the challenges. It is time for the Holy Grail War. The stage has been set, the participants are preparing. In the fight for this magical item of unlimited power, what will you be? Will you be a Master? A Servant? A Magus? Good or Evil? You decide...
