There is a butterfly in Yunshan, named Ruomeng. The body is as indigo as the sea, and the eggs are as bright as pearls. Round and huge, with the light of a real pearl. At the beginning of summer when the eggs hatch, black poisonous insects are born, named Xuan Zhen. Xuan's fine silk is as thin as a silver needle and is a rare treasure. If it is spun and cut, its clothes will remain intact and spotless even after years and months of use. A woman's clothes will make her body graceful and youthful forever. After half a year, Xuanzang turned into a pupa and emerged into a butterfly. This insect particularly likes to eat human organs and brains, but it is extremely evil to human eyes. Although the deceased has a peerless appearance, they all end up looking like skin and bones due to the lack of organs and brains.
When a rare treasure that can transform a woman's appearance into a fairy-like one and remains unbeatable over the years falls into the hands of an ugly girl who has been bullied in a brothel...