Age 10:
The same girl whose family had been killed just three years ago was sitting at the back in the Ninja academy. She looked to the front and seen a young boy, Naruto Uzumaki. She could tell from the minute she had laid her eyes on him that he was a Jinchuriki too. She didn't know if he knew it or not though and she knew that she probably wasn't supposed to tell him if he didn't know. She decided not to meet him as she was too afraid to. She just sat at the back of the class hoping not many people would notice her dragon eye.
People noticed. They made fun of her, they tormented her, they were just plain mean to her. One girl seen Kei's curse mark, even though it was sealed she told the rest of the class and they didn't take well to it. Whenever someone looked at her it was of pure disgust or horror. She completely lost it and went in full bijuu mode once. Almost everyone feared her after that.
By the time the final exams came around she passed with the highest scores, but there was also a problem. There was an uneven about of students that had passed. There were several teams as always but she was left out with no-one on her team. She didn't mind it at all because she knew it would be safer for them to not be on her team.