300 years ago, in a world where humans and mermaids coexisted, Radisha was an ordinary human living her life. One day, she met Buqu, the powerful lord of the sea and a mermaid, and they fell deeply in love. Despite their different worlds, Radisha and Buqu were determined to make their relationship work. However, their fairytale romance was cut short when a group of demon mermaids attacked and killed Radisha. As fate would have it, Radisha was reborn as a concubine in Buqu's court. Although she was no longer able to remained star-crossed lovers, separated by their different worlds but forever connected by their enduring love.