Nobita finds himself entangled in a peculiar dream featuring Roppel, a boy, and his odd friend Chami on a cosmic adventure. To his surprise, the dream becomes reality when he encounters them being chased through space, leading to a bizarre fusion of their spacecraft with Nobita's room. As they venture to Roppel's planet, a bond forms, prompting Nobita and Doraemon to aid in liberating the planet from its tyrannical rulers.