Start the quest by speaking to Olga Servo. With the now obtained Old Diary from the Mysterious Past quest, Servo accepts you as the person in her memory. Servo is still unable to tell you all she knows as the memory of the monsters attacking and of your family is too painful. She says your pendant is missing a fragment and tells you to ask Moneo Fuente about it. Head north to Moneo Fuente and he will give you your reward but requests that you do him a favor later.