Based on the Victorian-goth otome girl's game:

Hanna inherited her grandfather’s ability to make “elemental dolls,” but he forbade her to do that after she made her first doll, her maid Emily. After he died however, Hanna discovered a strange male “elemental doll” called Will in the basement of her grandfather’s workshop. Who made Will and for what purpose? Why is he calling her “master” and are there others llike him? These are only a few of the mysteries Hanna has to solve.

(Source: Baka-Updates Manga)