Project Ultraverse: Fate/Akai Tsuki

In a simple calm city a new war breaks loose.
The Holy Grail, the fabled object of great power has arrived in the city. An object that is supposed to be brought by the fabled Holy Grail War ritual from the East.
Normally there are 7 participants in this war, but not this one. The ritual is broken as an outsider participates without a Servant, what will this mean to the ritual?

The first part of The Ultraverse Crossover Project