Ritsuka Fujimaru (藤丸 立香, Fujimaru Ritsuka?) is the protagonist of Fate/Grand Order, acting as the Master of many Servants for the purpose of solving the Grand Order conflicts; however, the Servant they are most closely associated with is Mash Kyrielight. The name and gender of Ritsuka can be actively changed by the player, with the nicknames Gudao and Gudako being often used by fans for the male and female version respectively, rather than their proper name.

https://typemoon.fandom.com/wiki/Ritsuka_Fujimaru#:~:text=The%20name%20and%20gender%20of,rather%20than%20their%20proper%20name.