Tsuki no Sango

Overview

The story takes place in approximately the year 3000, when humankind arrived at the peak of its civilization, but is losing it's will to keep living. It follows a girl, called "princess" by those around her, living on a small island with a fifty person colony and a shinning coral reef. She is descendant of Moon people, and it focuses upon how her ancestor supposedly came to Earth.

Source: AniList