In 2063, space travel is commonplace and commercially viable. Aries Spring, an upbeat participant, heads to the spaceport for a camp on the remote planet McPa, only to have her purse stolen by a careless thief. Kanata Hoshijima, one of the athletic teens joining her on the excursion as part of team B-5, swiftly recovers it. Upon arriving at their campsite, the group experiences a sudden twist when a mysterious sphere of dark energy sucks them into deep space. Now stranded with slim chances of survival, they find an abandoned vessel that could be their ticket home. However, they soon discover they are thousands of light-years away from where they started. Confronting this harsh truth, the nine stranded individuals must meticulously conserve their supplies, maintain their stamina, and collaborate to navigate the dangers of space. Despite the unknown cause of their predicament, they embark on a treacherous voyage back home aboard their newly acquired ship, the Astra.