A girl who wants to become a knight to avenge her parent's death. However. She knows it is difficult for a girl to become a knight, but she hopes she can become strong enough to overcome their prejudice.
Probably a reference to the real Joan of Arc, a heroine who fought in the Hundred Years War. Her background is probably based on Hua Mulan's, a legendary heroine who pretended to be a male and took her aged father's place in the army.
The hero is promoted from a random hero of the same class which is a lower rank than the current hero.