Ritsuka Fujimaru is the protagonist of Fate/Grand Order, acting as the Master of many Servants for the purpose of solving the Grand Order conflicts. She has absolutely no background details or connections to other people or events. She is simply "someone who just happened to see a recruitment flyer at a station, applied and got accepted into the job, and somehow ended up getting taken into the Chaldea Security Organization.'' She is a rather mediocre magus with skills comparable to Lord El-Melloi II.

Spoiler

After the events of First Order, Ritsuka is the only magus available to tackle the Singularities thus becoming the epitome of the everyday woman tasked with saving the world