The nine strangers waking up on an empty ship in the middle of nowhere don't know each other yet. By the time they figure out how they got there, you've stopped caring about the mystery and started caring about whether they make it home alive. Every clue plants itself so cleanly that the final episode feels inevitable and earned, not lucky, the show respects your intelligence enough to hide nothing and reveal everything anyway. The writing wobbles in the middle, dropping character arcs like it forgot them, but the core survival logic never cracks. This is what happens when a show trusts its premise completely: nine kids, an empty ship, and thirteen episodes to find out if friendship is enough to survive space.

In 2063, space travel is commercially available, and the cheerful Aries Spring sets off for a weeklong camp on the distant planet McPa. At the spaceport, the athletic Kanata Hoshijima gets back her stolen purse, and she learns he is part of her group, team B-5. Soon after the nine teenagers reach their campsite, a strange orb of black light sweeps them into the depths of space. There they find an empty, drifting ship that could take them home, but they are thousands of light-years away. Aboard the ship, which they call the Astra, they must ration their resources, stay strong and pull together for the long voyage back. What cut their trip short is still a mystery. The show is a science fiction adventure with a mystery at its center.