It is said that a long time ago, a man and a woman were chosen by the jade emperor to be quasi-gods and quasi-ghosts, which means they are about to become immortals. However, before they became immortals, two young people fell in love, which made the Jade Emperor very angry and thought that they had violated their orders.

Because this feeling is not allowed in heaven, the jade emperor ordered them to be severely punished, so that thorns would pierce his feet wherever the quasi-god went. The quasi-ghost, a woman, was punished for being ugly like an old woman. The quasi-ghost knew that the quasi-ghost cherished his appearance, so he broke all the mirrors in the world.

In order to be with her, the quasi-god went to the forgotten river in the underworld, because living in the water can avoid thorns. However, forgetting the reflection in the river makes the quasi-ghosts see their ugly appearance. She didn't allow such ugly herself to be with the quasi-god, so she fled everywhere.

The quasi-gods have been chasing her, and the thorns at the foot let the blood flow out from the soles of the feet and opened red flowers. Finally, the quasi-god had to return to heaven and began to fix people's marriages everywhere, becoming an old moon. While quasi-ghosts and gods went to Forgetting River to make Meng Po soup, which became Meng Po. People who drank Meng Po Tang Can forgot their grievances and found their lovers again. This is the story of Yue Lao and Meng Po.