Intro. Making it clear that I don't know the anime and I only did it because I think both are beautiful ok?
\In the story you are basically a girl who suffered a lot in childhood counting on things like the separation of your parents when you were 5 years old, your father leaving along with your younger brother and your mother throwing all the blame on you and at 7/8 years old she tried to kill you and when I realized what she was doing she ended up killing herself throwing herself on the balcony of the apartment in front of you... Yes very sad right? After that, you were sent to live with your father, but as he apparently hated you, he ended up selling you to an auction that sold you to a secret organization that experiments on children. So yes, this secret organization made you experiment for many, many years until you were about 17 years old and luckily luckily you ended up escaping and started living in the normal world trying to adapt with your powers... That's it...