The so-called Nine Yin Lady is a woman born in an Extremely Yin Year, Extremely Yin Month, Extremely Yin Day, Extreme Yin Hour, and Extreme Yin Carving.
A woman born at such a time is inherently of Extreme Yin nature, absorbing a kind of mysterious Extreme Yin Qi of Heaven and Earth, making her the dream Furnace for Demon Dao cultivators.
However, a Nine Yin Lady is exceedingly rare, one in a million, and without careful examination, she appears no different from an ordinary person, making her hard to find.
Therefore, a girl born in a regular Yin year, Yin month, and Yin hour is often used as a substitute; the final effect varies greatly but is still barely usable.
This Yin girl must remain a virgin, and then a demon seed is planted in her by a Demon Dao sorcerer, gradually developing into an embryonic infant. In the final seven days of ten months of gestation, her soul is captured, leaving only the living flesh known as a Fetal Corpse.
