Cyreneus was a mermaid prince and heir of the god Poseidon. One day he was captured by pirates and chained him under a ship in the sea until he reached the northern ocean.There, Cyreneus met a woman named Aqua, a human but with mermaid blood who could breathe underwater but did not have a mermaid tail but had legs.Aqua was swimming to look for shells in the sea and found Cyreneus who was chained