When a new emperor takes office, a ghost takes a wife; this has been the age-old principle. But nowadays the court is monogamous, and with 9 ghosts for 12 wives, there are too many potential wife candidates. Not to mention the ghosts who do not want to ascend to be palace masters, this is why all the past ghostly brides have fought for their husbands.
This year's new emperor is even more so misguided with his drunken behaviour. With one thing leading to another, the new emperor accidentally drinks too much and finds that all the ghostly brides were written as men. This might just be a million years worth of bad luck…