In the year 2125, the Starbridge had a climax of its own interstellar wanderings. The people put down the lifeboat Nebula and sent the rover Chen Zilan and her mechanical partner D-18 on a solo voyage, expecting them to explore the unknown secrets of the universe.

Just when they are full of hope and ready to find the unknown, the Nebula crashes unexpectedly. When the mechanical explosions stopped, they landed in the depths of a lonely planet called Lv-433. When the wreckage is gone and they open their eyes, they can no longer find each other: they are lost...…