The anime's original story features Mutta and Hibito during one summer when they were children. During the summer when Mutta and Hibito made their promise to go to space, they met a young girl who also had a wish. (Source: Anime News Network)
Genres: Comedy, Sci-Fi, Slice of Life
Watch Planetarium Uchuu Kyoudai: Itten no Hikari online — subbed and dubbed, with automatic AniList / MyAnimeList progress sync.