Francisco Xavier

A Christian Saint.
A missionary who arrived in Japan in 1594.
He was posthumously designated as a Saint after spending his life traveling around the world spreading the word of God.
In the main storyline of Fate/EXTRA, upon entering the nameless forest the protagonist might suddenly let loose a mysterious strange voice saying something that resembles the name of this great man… This is one of the seven great mysteries of SE.RA.PH.

Fate/EXTRA Material: Encyclopedia of Fate/EXTRA