The Lesser Grail Wars. In the aftermath of the theft of the Greater Grail by the Yggdmillennia family, the proliferation of the ritual by which seven Mages summon seven Servants to fight for the Holy Grail was nigh-inevitable. The majority of these wars, in spite of being fought over an object much less powerful than the Greater Grail, have resulted in disaster and a significant number of deaths among the Mage population.
As a Lesser Grail War looks to kick off in Ireland, a modification to the ritual results in a much more powerful Grail, able to summon seven Heroic Spirits of power exceeding most Lesser Grail Wars. In an effort to limit the scope of the damage, Niamh, the scion of a reclusive family of power brokers, enters the war as the Master of Rider.
But there's only so far you can go with a wish to protect others, and Niamh will have to find the answer to why she fights before the War threatens to undo her world, and her with it...