It was the forgotten EXTRA.

This is a story of EXTRA that will unfold on a forgotten moon.
The Mooncell Automaton, a spiritron computer that exists on the moon, grants any and all wishes.
A virtual spiritron world created within the Mooncell is SE.RA.PH. With the "Holy Grail" on the line,
Wizards and Servants must now wage a brand new Holy Grail War of the Moon.