Hisui

The younger of the two twin maids in the Tohno mansion. She wears a western maid uniform and attends to Shiki when he comes back to the Tohno mansion. Her name, Hisui, is the Japanese word for jade, referring to her eye color.

[Spoiler] She acts cold and unfeeling, but it is only an act to hide her kinder nature for the sake of her sister. She is a Synchronizer, a person that can give someone life energy through the exchange of body fluids. [/Spoiler]