Hyou Eiki is Sa Enjun's consort. She remained in the Sa Province to act on his behalf as the clan head while he carried out his duties as Taiho in the imperial capital. Much of their long marriage was spent separated in this fashion. After Enjun's death, his ambitious younger brother Chuusho imprisons her and Shunki.

Eiki was born to the Hyou clan, the mysterious shadow lineage of Saiunkoku. As such, she would not have normally married outside her family, but she fell in love with Enjun and pursued him until he gave in. She retained some of the supernatural powers of the Hyou women, such as the precognition which turned her against Advisor Sho because she always knew that he would be involved in Enjun's death. She also sealed off the powers and voice of their granddaughter Shunki during the girl's childhood.