The story of Planet Tero tells about a beautiful planet where the inhabitants are tolerant and friendly. However, due to over-exploitation of resources by humans on Earth, it is no longer suitable for living. They have to find a new planet to settle on. As a result, humans discover that they can use a certain technology to alter Planet Tero to make it suitable for human habitation, but at the same time, this new environment would be fatal to the planet's residents. Mara is an precocious girl from Planet Tero. By chance, she rescues a human pilot and takes care of him until he recovers. The two plan to work together to resolve the crisis on Tero, ideally allowing for peaceful coexistence between Earth humans and the residents of Tero.