The Holy Grail War is a battle royale among seven magi who serve as Masters. Masters, through the use of the command seals they are given when they enter the war, command Heroic Spirits known as Servants to fight for them in battle. In the Fifth Holy Grail War, Rin Toosaka is among the magi entering the competition. With her Servant, Archer, she hopes to obtain the ultimate prize—the Holy Grail, a magical artifact capable of granting its wielder any wish. One of Rin's classmates, Emiya Shirou, accidentally enters the competition and ends up commanding a Servant of his own known as Saber. As they find themselves facing mutual enemies, Rin and Shirou decide to form a temporary alliance as they challenge their opponents in the Holy Grail War. [Written by MAL Rewrite]

In the midst of the Fifth Holy Grail War, Caster sets her plans into motion, beginning with the capture of Shirou's Servant Saber. With the witch growing ever more powerful, Rin and Archer determine she is a threat that must be dealt with at once. But as the balance of power in the war begins to shift, the Master and Servant find themselves walking separate ways. Meanwhile, despite losing his Servant and stumbling from injuries, Shirou ignores Rin's warning to abandon the battle royale, forcing his way into the fight against Caster. Determined to show his resolve in his will to fight, Shirou's potential to become a protector of the people is put to the test. Amidst the bloodshed and chaos, the motivations of each Master and Servant are slowly revealed as they sacrifice everything in order to arise as the victor and claim the Holy Grail. [Written by MAL Rewrite]

With the promise of granting any wish, the omnipotent Holy Grail triggered three wars in the past, each too cruel and fierce to leave a victor. In spite of that, the wealthy Einzbern family is confident that the Fourth Holy Grail War will be different; namely, with a vessel of the Holy Grail now in their grasp. Solely for this reason, the much hated "Magus Killer" Kiritsugu Emiya is hired by the Einzberns, with marriage to their only daughter Irisviel as binding contract. Kiritsugu now stands at the center of a cutthroat game of survival, facing off against six other participants, each armed with an ancient familiar, and fueled by unique desires and ideals. Accompanied by his own familiar, Saber, the notorious mercenary soon finds his greatest opponent in Kirei Kotomine, a priest who seeks salvation from the emptiness within himself in pursuit of Kiritsugu. Based on the light novel written by Gen Urobuchi, Fate/Zero depicts the events of the Fourth Holy Grail War—10 years prior to Fate/stay night. Witness a battle royale in which no one is guaranteed to survive. [Written by MAL Rewrite]

As the Fourth Holy Grail War rages on with no clear victor in sight, the remaining Servants and their Masters are called upon by Church supervisor Risei Kotomine, in order to band together and confront an impending threat that could unravel the Grail War and bring about the destruction of Fuyuki City. The uneasy truce soon collapses as Masters demonstrate that they will do anything in their power, no matter how despicable, to win. Seeds of doubt are sown between Kiritsugu Emiya and Saber, his Servant, as their conflicting ideologies on heroism and chivalry clash. Meanwhile, an ominous bond forms between Kirei Kotomine, who still seeks to find his purpose in life, and one of the remaining Servants. As the countdown to the end of the war reaches zero, the cost of winning begins to blur the line between victory and defeat. [Written by MAL Rewrite]