Fuyuki Church

The church used as a base by Kotomine Risei, supervisor of the Fourth Holy Grail War. Also responsible for the protection of Masters who have lost their Servants. Fuyuki Church is the location the Holy Grail was summoned in the Third Holy Grail War.

Fate/Zero Animation Guide I: Glossary of the holy grail war I

A church modestly standing in Shinto, at the east side of the Mion river. It became the base of the character with the role of supervisor of the Holy Grail War.
Currently, Kirei is working as a priest… He should, but it seems he is mostly away. Without any believers to visit it either, the raising of plants has also been completely forgotten.

PRISMA material/petit: Encyclopedia of Prisma Illya MOVIE