Long ago, humans used to live underwater in cities of their own making. To live here, they were blessed with a special layer over their skin called Ena. At some point, a group of humans decided they wanted to live on the land and went up to the surface. This created a division between the two groups that would be known as the sea people and the land people. Hikari, Manaka, Chisaki and Kaname are childhood friends in the Sea Village Shioshishio.
Fisherman Caught a Sea Girl And Starts Living With Her