An eighteen-year-old lawyer named Shemin meets a twelve-year-old girl, Milu, at an orphanage. He tells her that she can inherit Dr. White's vast fortune if she can make Dr. White's zoo thrive. After Milu moves into the zoo, she and Shemin discover a secret underground laboratory. At the same time, a mermaid pulls them into a royal rivalry. Prince Adam plans to create powerful hybrids by combining humans with animals through genetic experiments in a bid for power. However, his scheme is thwarted by Shemin, Milu, and their friends. Although Milu initially misunderstands Shemin, their bond grows stronger with each passing day.