Story
The setting is Fuyuki City, a city surrounded by the sea and mountains.
In this ordinary city, there is a darkness slowly encroaching.
　 　
The Holy Grail is said to grant the wish of whoever possesses it.
In order to materialize the Holy Grail, a ritual is about to take place.
To the seven Masters chosen by the Holy Grail, seven Servants chosen by the Holy Grail will be given.

Saber
Lancer
Archer
Rider
Caster
Assassin
Berserker

A Master must make a contract with a spirit bestowed with one of these seven classes, and prove themselves worthy of the Holy Grail.
In other words.
One who becomes a Master must eliminate the other Masters and show that they are the strongest. The entire quest for the Grail is called the 'Holy Grail War'.
The ritual that takes place in this land is, true to its name, a 'fight to the death'.
　 　
The protagonist, who lost his parents in a fire when he was young and became an orphan, was taken in by someone who claimed to be a sorcerer.
Despite his adoptive father's objections, the protagonist learns magic, but he has no talent at all and only learns one type of magic over the years.
His adoptive father is now deceased, and the protagonist grows up to be a half-mage.

And now in present day.
The protagonist accidentally gets caught up in a battle between Masters, and happens to make a contract with Saber, one of the seven Servants.
Unwillingly becoming one of the Masters, the protagonist ends up throwing himself into the battle for the Holy Grail────