Kiritsugu Emiya's assistant during the fourth Holy Grail War.
As a child, she is forced by the army to fight in a war. At some point, soldiers kidnaped her and raped her. After losing her child, she lost everything. When Kiritsugu met her for the first time, he took Maiya as his mentee and trained her as an assassin. To Maiya, Kiritsugu gave her a name and a purpose.
Maiya Hisau is created by Gen Urobuchi and designed by Takashi Takeuchi as one of the supporting characters for the Fate Zero anime series. She originally appears in the visual Fate Zero, and makes her first anime debut in Fate Zero episode 3, The Land of Fuyuki. She is voice by Ayumu Tsunematsu in the Japanese version.