19年前，亲密无间的南波兄弟在晴朗的夜空下目睹UFO出现，这一事件直接影响着兄弟俩未来的人生。2025年，弟弟日日人（冈田将生 饰）将作为首位登上月球的日本宇航员，与NASA的伙伴们展开传奇之旅。而他的哥哥六太（小栗旬 饰）则以概念汽车设计师的身份打拼，却因头槌攻击上司而被开除。正是人生颓败之际，六太接到来自JAXA（日本宇宙航空研究开发机构）的首轮测试合格通知书。原来，日日人念念不忘当年和哥哥的约定，兄弟俩要携手登上月球。在弟弟的鼓动下，六太重燃对宇宙的憧憬，与一群有着共同志愿的人们展开集训。另一方面，日日人和伙伴登陆月球，迈开至关重要的一步，然而意外发生…… 　　本片根据小山宙哉的同名漫画改编，三度漫步太空的日本宇航员野口聪一以及第二个在月球上留下脚印的美国宇航员巴兹·奥尔德林也在片中客串。One night, as children, Mutta and Hibito saw what they thought was an UFO passing close to the Moon. Becoming fascinated by space, they promised each other they'd be astronauts and that one day they'd meet in outer space. Years later, Hibito, the younger brother, has been selected as the first Japanese astronaut that will participate in a mission to the Moon. Meanwhile Mutta, the older one, had given up on those dreams and has recently lost his job as a car designer. It's then that he receives a call from his brother who asks him to remember that one night of their childhood and their promise.