Yin Yang Devils were two corpse devils that were once a pair of Dao companion elders from a previous generation. They both possessed early Nascent Soul stage cultivation but they had betrayed the Harmonious Bond Sect for some reason or another and turned to the path of the Ghost Dao, transforming themselves into living corpses. Later when the two made great sweeps in their cultivation, they wished to exterminate the Harmonious Bond Sect, killing over a hundred disciples before they were finally captured alive by several sect elders. By taking advantage of an ancient technique to erase their consciousness, they were refined into the legendary Yin Yang Corpse Devils. The Corpse Devils were more powerful than when they were once alive.
Yin Yang Devils rest in 2 huge coffins, one black and one white, being covered with dozens of various-colored talismans. They are tended by 16 male and female disciples. Ater being released, Yin Yang Devils consume the blood essence of one virgin man and woman. They can be steered by cultivator using green-bronze plates engraved with talisman characters.
Yin Yang Devils looked like a young man and woman, both possessing delicate appearances and completely lifeless eyes, but they can transform into having red hair, green skin and grew to six meters in height.