This is a Naruto and Fate/Stay Night crossover. If you have understanding of the Fate universe feel free to skip this. For those who aren't familiar with the Fate universe there will be a short explanation. For those who haven't read/seen Naruto, you don't need to have knowledge of the characters. There will be some things that might go past you but other than that you will understand the story and I am positive that it will be enjoyable too.

I have changed few terms to better fit the lore of Narutoverse so I included all changes here:

Holy Grail = Chakra Fruit

The church = The tree

Einzbern family = Sabaku family

Toshaka family = Hyuuga family

Matou family = xxx family (unknown)

Fuyuki City = Konohagakure

Holy Grail War = Chakra Fruit War

For those who aren't familiar with Fate universe (I will be using terminology used in the story):

Every x years, in a city named Konohagakure the Chakra Fruit, able to grant any wish, appears and seven mages known as masters fight for it. Each master summons one servant, a hero from history (original show examples: King Arthur, Alexander the Great, Medusa, etc.). These servants are divided into seven categories based on their skills. There is always a servant from each category in each war.

The masters and servants usually cooperate (but the don't need to, for example Gilgamesh and Tokiomi Toshaka in Fate/Zero) but each master has three command spells that the servant must obey without question. Ideal situation is when the master and servant fight in close cooperation.

Servants are able to use magic but they use their masters mana. They can also physically disappear from the real world. The servants also run around the world by themselves in normal clothing but they can instantly change to their original appearance. Servants can in theory stay in the real world until they are killed.

Each servant has one or more special skills called Noble Phantasm. It is an ultimate attack usually somehow connect to their past and skillset. It is crucial that no-one except allies knows servants original life because then it is easy to figure out the Noble Phantasm said servant has. Some servants can be easily recognized by small things (for example: King Author = Excalibur).