The year 2025. My brother believed in himself just one more time. The story of his journey to Mars via Tsukuba begins! A full-fledged sibling space manga is launched! In the year 2025, the elder brother Rokuta and the younger brother Hibito made a promise while gazing at the starry sky, and as promised, the younger brother has become an astronaut and is a member of the first long-duration crew on the moon. On the other hand, Rokuta is unemployed after being fired from his job. A single email from his younger brother sets him off to explore space again!