At the beginning, it showed a red-haired woman who was dying. Then she was in front of a man who greeted her familiarly and said something like "so you're here again?" because she died. I'm pretty sure he had red hair too but I don't know.
It's then revealed that she has died five times prior, all of them before her 25th birthday. He then gives her an amulet with four stones in it and explains what they're used for, except for the last one, because she eats the sweet-like reincarnation stone.
She is reborn in the same world as before, as per their deal, but she is reborn as a noblewoman with white hair and striking green eyes. But because she wants to be able to protect herself and live past 25, she eats the stone that allows her to become whatever she dreams to become a knight and gain strength.
She finds a blond man in the middle of the woods who is very hurt and she uses the stone that cures all diseases. The man turns out to be the son of the king or emperor . She also uses a magic sword thing in the middle of a tournament. Also the royal family has blond hair, if that helps.