Hagure Ningyo no Diana

Once upon a time, in a land far away, there was a lone mermaid who was brought to a castle.  The mermaid was rather unusual because her tail end had separated into two, and it was said that they planned to present her as a gift to the king of a neighboring country... But when the prince saw the mermaid, he asked her, "Won't you be my queen?!" Ever since then, the two start living together... much to everyone's surprise! Will the love between these two lead them to a happily ever after?!