Before the real Holy Grail War begin, there will be a selection tournament that will be held across the Europe. The Midsummer Selection Tournament purpose is to choose seven duelist who are worthy for the Holy Grail. The Tournament itself is held during Midsummer in secret or in disguise and can only be participate by the family member of the chosen family. The founder of the tournament is the Xavier family, one of the chosen who is also assign by Calliope as a host for the tournament in exchange of wealth and prosperity. Seven tournament will be held and the winner will be able to participate on the Holy Grail War.

There is no turning back from Midsummer Selection Tournament. The each battle is a "Game of Darkness" and the loser will lost their soul for Calliope to consume.