Ten years before Fate/stay night, seven mages summon legendary heroes as Servants and fight the Fourth Holy Grail War in Fuyuki City, a winner-take-all contest for a Grail said to grant any wish. Kiritsugu Emiya enters on behalf of the Einzbern family: a mercenary who once dreamed of saving everyone and now wins by any means, paired with the proud knight-king Saber. Around them, rival Masters and their Servants chase clashing ideas of heroism. Gen Urobuchi wrote this light novel as a prequel to Type-Moon's Fate/stay night.