The stage is a city surrounded by the sea and the mountain · Fuyuki-shi. There was a dark erosion little by little in this town where there was no choice. Holy Grail that will fulfill wishes of those who got it.
A ceremony was about to take place to realize the Holy Grail. Give seven magicians (masters) chosen as the Holy Grail, the Seven Horsemen's choice (servant) chosen by the Holy Grail. Knight "Saber" Spearman "Lancer" Archer "Archer" Cavalry "Rider" Mage "Caster" Assassin "Assassin" Berserker "Berserker" Master contracted with one of the seven roles (class) Then you must prove that you are fit for the Holy Grail.
In other words. Those who became the master must erase other masters and show themselves to be the strongest one. All the acts seeking the cup are called "Holy Grail War". The ceremony that happens in this place can be called "killing" which is not ashamed of its name. When I was young I lost my parents due to a fire, and the hero who became an orphan is taken over by a person who calls him a magician.
Although he is the hero who learns magic by giving objections to his adoptive father, there is no talent at all and only one magical skill has been acquired over the years. The adopted father also dies now, the hero grows as a magical master of half a servant. And so now. The hero who was caught in the battle between masters from the start triggered a contract accidentally contracts with Saber, one of the seven servants. The hero who became one of the masters undesirably will throw himself into the fight over the Holy Grail