Nobita dreams of a boy named Roppel and his strange companion Chami traveling through space. One day he meets them in person, discovering that they are real and that they are being chased by hostile forces, which causes their spacecraft to malfunction and connect with Nobita’s room. The group travels together to Roppel’s home planet, where they enjoy a brief respite before Nobita and Doraemon pledge to help free the planet from its oppressors.