This is based on a legend in Ancient China:

Luuzhu (Green Pearl) is a beautiful pearl gatherer from a small Southern village in Ancient China. Due to her family's poverty, she was sold by her parents to be the mistress of the wealthy but abusive and old Lord Hong. However, Fate is not so cruel to the gentle Luuzhu. Just before her marriage to Lord Hong, Luuzhu met a young handsome nobleman named Jilun on the beach at night. Dazzled by Luuzhu's grace, Jilun purchased her from Lord Hong for ten bushels of pearl (a most generous amount at the time). It turned out that Jilun is one of the richest man in Ancient China! However, Lord Sima Lun, who usurped the throne, now desires Luuzhu for her legendary beauty. He is even willing to go to war with Jilun for her! Will Luuzhu become just another plaything for the rich and privileged, or will she avert from that terrible fate? Or perhaps, will her celestial beauty bring woe upon her and her loved ones?