Height: 156 cm

The younger of the two twin maids in the Tohno mansion, Hisui is a childhood friend of Shiki. 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.

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

Hisui was a member of a branch family of the Fujou clan, but was brought with her sister Kohaku to live in the Tohno mansion, because the Fujou clan had a special power of giving others energy. Makihisa Tohno needed this ability in order to keep control of his body. Hisui, however, was never forced to utilize her abilities as a Synchronizer because of the pleas of Kohaku and instead found herself living as a normal girl.