A história conta as aventuras do menino, 21 emon, há anos que dirige um hotel de sua família. Em seus problemas, 21 emons são ajudados pelo robô Gonsuke e o pequeno alienígena Monga.
The story tells the adventures of the boy, 21 emon, engaged in the management of a hotel belonging to his family for years. In his problems, 21 emons is helped by the robot Gonsuke and the little alien Monga.
本片改编自藤子・F・不二雄所创作的太空科幻题材同名动漫作品，由常年担任大山版哆啦A梦电影的芝山努导演所执导，于1981年暑期上映。人设基本遵从原作，全片故事可以说是原作...
21エモンは、オンボロホテルつづれ屋の跡取り息子。つづれ屋廃業のピンチをのりきって、絶対生物のモンガーやイモ掘りロボットのゴンスケと、太陽系一周の冒険旅行に旅立つ...
