Prasino was a powerful kingdom. Its King had captured the mighty Sea Goddess and used her powers to wage war against other kingdoms. For many years, Prasino was at war with Kokkino, who wanted the Sea Goddess for their own purposes. Unknown to the family, the King's Chancellor, John, was the King of Kokkino's, spy. John tricked the King into summoning the Goddess. However, John ventured into Kokkino in order to save Teresa and Daphne, two of the Prasino Princesses. Their boat went to near Kokkino and Bluebeard captured them. After witnessing what the king did to the princesses and discovering that he had murdered his wives, including the one who showed John kindness, John turned his back on Kokkino and saving the Princesses and setting sail for Prasino. Unfortunately, the angry Sea Goddess erupted from the sea and caused the ocean to rise, flooding the two kingdoms and drowning everyone except the royal family of Prasino.
The Goddess cursed the family. The King was transformed into a monstrous crab-human hybrid and his daughters were turned into mermaids. For many years, they lived in their palace beneath the sea, guarded by a fearsome eel. However, one day, the Sea Goddess told the King that if he gathered the five elemental orbs, they could charge a machine that would restore his human form. She demanded that his daughters find the orbs because, once they touched an orb, the mermaid would become human again. The daughters set out to look for the orbs.
One daughter, Naida, became careless after years of searching. One day, she was caught by fishermen. The greedy men trapped the mermaid Princess and showed the miraculous mermaid off. Naida despaired and feared never becoming human again. Hope came in the form of a frog; James the Frog Prince fell in love with the beautiful mermaid and helped her escape. Naida was so grateful that she kissed him. James' curse was broken and he became human. He journeyed across the globe, searching for the metal orb so he could be with his aquatic Princess. He found it and Naida was restored to human form. They lived happily until Naida's death; once she became human again, she lost her mermaid immortality and died. The grief-stricken Prince became a frog once more. Later, after his divorce with Snow White, he built an underground palace and created a shrine to his little mermaid.
The second daughter, Calliope, searched the oceans for the water orb. She encountered a sunken ship. Among the debris was a Prince. Calliope rescued him. Calliope fell in love and became more desperate to find the orb. She traded her beautiful mermaid voice to a mysterious sea witch who used her magic to find the orb. Calliope journeyed ashore and the Prince, enchanted by the beautiful silent stranger, invited her to stay. Unfortunately, Calliope's happiness ended when the Prince married another Princess. However, Calliope heard of an assassination. On the day of the Prince's wedding, Calliope saw the glint of the weapon that was about to kill the couple. Calliope could not let them die so she ran in front of them and before anyone realized, including the assassin, Calliope was dead. The Prince was heart broken. He prepared a royal burial at sea. As the former mermaid's body descended into the sea, her beautiful form dissolved into foam.
Another daughter, Teresa, was adventurous. She longed to explore the woods and mountains. She swam near the forests along the coast of France. There she met a young Eldra and Raphael. They helped her find the fire orb. Along the way, they became friends. Once the orb was found, Teresa became human and joined the Red Riding Hood Sisters. She later became the Elder Sister. Unfortunately, years later, she was betrayed and murdered by her friend Eldra, who became the Wolf Queen.
The King's youngest daughter, Daphne, also found her orb, the nature orb. She regained her human form and left the sea. It is unknown how she found it, or what eventually became of her. She may have been killed, but most likely, if she found her orb around the same time as Teresa's, she may still be alive. If she found it long before, she may have regained her mortal form and died of old age.
The final sister, Althea, could not find her orb. One day, a grown Pinocchio arrived in Prasino along with the Fairytale Detective. The eel swallowed the man up, but thanks to the Detective, who poisoned the eel, Pinocchio was saved. However, his orb needed to be recharged; the wooden orb was with Pinocchio all along. Gepetto used it to bring Pinocchio to life. The Detective recharged the wood orb and gave it to Pinocchio. However, an enraged Althea leaped out of the water and grabbed the orb. She then became human. Her father took the orb and blocked the door with a magic barrier. The Detective found an ally in the mermaid-turned-human when the Detective rescued her from a pit of piranhas. Althea helped the Detective save her father and later, after the palace was flooded, she swam with everyone back to shore. She helped the Detective soothe the angry Sea Goddess. Althea then thanked the Detective and went with her father to help him revive Pinocchio.
From oldest to youngest, the sisters are ordered: Naida, Calliope, Teresa, Althea, and Daphne