She is the Master of Archer in the False Holy Grail War in Snowfield. Tine's people are an indigenous people who had apparently kept watch over the Snowfield region for a thousand years before, in the early twentieth century, they were driven out by the government and the group of magus looking to prepare the land for the False Holy Grail War. Tine participates in the War seemingly with the intent to return her people to their rightful place. She does not have a particular wish for the Holy Grail to grant.
(Source: Type-Moon Wikia)