While looking for the legendary Mapman, the last surviving member of the Nomad Star tribe, Lipumira finds him in Tokyo. His name is Tokishima Gen and he is the only one who can retrieve one part of the star map hidden within the Earth.
After retrieving the piece, Gen must make a decision to either follow Lipumira in her foolhardy search to find the remaining pieces of the star map or rather stay on Earth. He decides to leave Earth, only to find out that his girlfriend has beaten him to the spaceship since she wants to come along as well. Unfortunately, as Gen learns the secret of the star map, Lipumira's sisters appear, planning to stop her at any cost.
(Source: Anime News Network)
— Description from AniList community (anilist.co).
