Ayaka Sajou, who comes from a prominent magus family, is widely expected to take part in the Holy Grail War. But, since since her father and sister were slain in the previous war, she has become depressed and hesitant to get involved in the issues that killed her loved ones. Soon after, she finds herself in great peril at the hands of a knight, prompting her to call her own Servant, Saber. With him at her side, Ayaka eventually becomes an official participant in the conflict she had hoped to escape.