Coral of the Moon

Tsuki no Sango takes place in approximately the year 3000, when humankind arrived at the peak of its civilization, but is losing its will to keep living. The story follows a girl, called "princess" by those around her, living on a small island with a fifty-person colony and a shining coral reef. She is a descendant of the Moon people, and it focuses on how her ancestor supposedly came to Earth.