Menae was Cordelia's mother and biological aunt of Carla and Shin.
She was the last firstblood woman and Karlheinz gave her to the Demon Lord as a mistress so Karlheinz could have children with their daughter - Cordelia. She soon died after Cordelia's birth.
She is sister of Krone, making her aunt of Carla and Shin; although she was like a mother to them.
It's also said that she had a piece of jade jewelry containing all of her memories, which she always kept locked away in a small silver box.