Mahou Tsukai no Yome: Hoshi Matsu Hito The Ancient Magus' Bride: Those Awaiting a Star
Three-part OVA chronicling a story taking place before Chise meets the Magus.
Chise is the student and future bride of the Thorn Sorcerer, Elias. They receive a package from Angelica in London: mostly textbooks, save for one special book.
Part 2 & 3:
The magician of the forest invites Chise into his library. Chise is reluctant at first, but they develop a strong friendship that would have a lasting influence on her.