Plurk paste

to become a magical girl, she had to make a contract with a creature named kyubey, who granted her one miraculous wish in exchange for her shouldering the duty of fighting other creatures called witches (which are in truth magical girls who succumbed to despair and became monsters; the fate of all magical girls if they don't die first. this is something kyoko knows now). the wish she made was for the sake of her father, a preacher who had been ex-communicated from the church for starting to preach outside the bible (and as a result dooming her family to poverty)

she wanted people to at least listen to what he had to say, and that's what her wish was -- the result was that a mass of people were brainwashed / hypnotized into attending her father's church. this gave her the power to make illusions, which she usually used to make ninja style copies of herself

eventually, her father found out what she was and what she did, and it made him very unstable. he felt she didn't have faith in him and made a deal with a devil and became a witch. he fell into alcoholism and spiraled downward, until finally he ended up killing their entire family -- her mother, her little (kindergarten aged) sister, and also himself -- and burning their home down while kyoko was away

kyoko blamed herself entirely for the situation, and came to the conclusion that it was her wish that brought ruin to her family. she chose to reject the part of herself that made that wish, including her concept of selflessness from then, deciding to instead live a self-interested life. but in rejecting her wish, she rejected the unique power that came with it, and had to re-learn how to fight to survive