Due to a warp in hyperspace, Nobita suddenly finds that the tatami (straw) mats in his room have turned into vessels that are able to fly through outer space. At the controls are a space immigrant boy named Loppel, and a rabbit from outer space called Chammy. The pair takes Nobita and Doraemon on a fantastic adventure to the scenically lush and verdant planet of Koya Koya, where they encounter Morina. Due to the lack of gravitational pull, Nobita finds that he is able to fly around like Superman. Learning of a sinister plot being hatched by the Galtite mining industry to take over the planet, Nobita enlists the help of Doraemon and his other friends to fight these forces in order to save Loppel and the others.