In Fuyuki City, the Holy Grail War is a long-standing ritual, wherein seven magi and their skilled servants fight to emerge victorious and have their wishes granted. Rin Toosaka intends to continue her father's legacy by joining the fifth iteration of the War and summoning the most capable class, Saber. But her plan goes awry, and she accidentally summons Archer instead. This unexpected turn of events leaves Rin wondering how she will fare in the upcoming battles.