Hoshi to Tabisuru

In a world where a "Super Proximity Satellite Cluster" surrounds a mother star, Genji, who lives on a small house planet, found a girl wandering around named Luna who had lost her memory, and rescued her from the dangerous ocean! The two of them who were driven by the dream of creating their own paradise, depart to the distant "Star Journey!"

(Source: Kodansha, translated)

Note: Includes two extra chapters.