Chigaeshi no Miko
She’s mother of Kazane. She resides in the Overturned Earth, a realm between the human world and the underworld where the guardians of the underworld protects her and her family, large animals whose duty is to serve the Priestess and protect the seal of the Underworld. Fifty years before the Kazane arc began; she sought the help of onmyōji Seimei and Ryūsai to help her seal the gates of the underworld since the seal was getting weaker. However, Ryūsai fell deeply in love and kidnapped her instead. She later left Ryūsai to go back to the realm but was kidnaped by Chishiki no Gūji. He sealed her into a frozen rock since he couldn't get her to open the Underworld gate; instead, he used her daughter, Kazane. She was later found and rescued by Seimei.
However, she was later in grief when she found out her daughter, Kazane died. She later brought back her daughter's body back to her home and gave Rikugō her necklace as a sign of gratitude for protecting her daughter.(Source: Wikipedia)