Esperanza was at a convention when she found a really cute pen on the floor. She was tempted to keep it, but decided to take it to the lost and found in case its owner was looking for it. On the last day of the con, during it’s final hour, as she was passing the lost and found the volunteer called out to her and told her that no one had come to claim the pen. The volunteer noted that Esperanza had really liked the pen so he gave it to her. 

Little did Esperanza know that she was supposed to find that pen so she could become Magical Girl Mariposa.