The Siren of the Palace— Episode 30

Aurora and her sister Sunset are two ageless mermaids on the Fountain of Immortality. Sunset, who is kind by nature, was tricked into the palace by Susan. Aurora enters the palace in order to avenge for her sister. At the same time, after getting Sunset's Soul Pearl, Susan is favored by the emperor. But the aftermath of Susan's agelessness spell makes her suffer a lot. Aurora gains Susan's trust step by step in the name of keeping Susan young forever. Finally, when Susan is about to be appointed as Noble Princess, Aurora reveals Susan's real face and avenges successfully.