A maid for the Tohno family, responsible for household chores (except cooking) and taking care of Shiki. She is Kohaku’s younger twin. Unlike her sister, she is known for wearing more modern, non-traditional clothing. Her quiet nature makes her true feelings difficult to read, and her formal way of speaking has led Shiki to see her as being rather mechanical. Her fighting skills are not quite on the same level as her sister, but she holds her own well enough.
The official website lists the following so far:
- Kouma Kishima
- Arcueid Brunestud
- Akiha Tohno
Hisui appears as a stern young woman, but actually she is a kind, loving and emotional girl, hiding her emotions to keep her sister as she is, due to the incident with Makihisa. Seeing Kohaku acting happy as Hisui was as a young girl, she cannot bring herself to return to her former self. Even if Kohaku is simply acting out her old role, she seems to have attained some level of happiness.
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. When Shiki Nanaya arrived to the Tohno house, at first he was unwilling to adapt to his new home, still traumatized for the death of his father. However Hisui was the one who encouraged Shiki to go out and play in the house. Her childhood was pleasant, and even though she is not naturally an active person, upon seeing Shiki playing so energetically she did her best to keep up with him.
After Shiki went to live with the Arimas, Hisui learned that Makihisa raped Kohaku so she becomes depressed. Kohaku, noticing this, promises Hisui that she will “take on her role” until she was cheerful again. Ironically, it is because of those words that Hisui is unable to return to her old self.