|Act II - L'Academie, girl in east Classroom at Night||Chronocrystal|
Return to L'Academie during Act II and shift the time of day to night. Head into the Classroom where the Priest is located and you'll notice a girl looking out of the window. Upon speaking to her you discover that she's a ghost and has one last request before passing on to the next life.
To track down the treasure in question, head to the The Warrior's Rest Inn at the Zwaardsrust Region and head to the hay field to your east. In the middle of this field you'll spot a gravestone which when inspected, will be that of Maxie and is indeed her most precious treasure. Return to the girl in the Classroom and inform her to complete the quest.