Nanase Ohkawa (七瀬), a member of the all-female manga-creating team Clamp
Neither Clamp writer Nanase Ohkawa or anime director Morio Asaka were satisfied with any of the voice actress who auditioned for the role.
Her duties in the team are Nanase Ohkawa's sounding board, and the character designer of Chobits and line artist for Tsubasa: Reservoir Chronicle.
Subaru and his twin sister Hokuto, as well as Seishirō, were first conceived by series creator Nanase Ohkawa for a dōjinshi novel about an onmyōji who hunts elves, of which only the beginning exists.