Emilico is merely one of the many "Living Dolls" employed at the Shadows House, where the residents are jet black from head to toe and perpetually leak soot that stains the mansion black. Every "Shadow" is paired with a Doll, who oddly resembles their partner. As a Living Doll, Emilico is required to keep the house spotless and serve as the face for her master, Kate. In return, Kate supports Emilico and treats her as a confidante. As far as either of them can recall, this has always been how their world functions. However, the nature of the bond between a Shadow and a Doll remains unclear. Administrators oversee the young pairs from the upper floors of the mansion and judge them—but for what purpose?