Planet Catcher Corporation is leading the charge in mankind's exploration of space in the mid-21st century. Their pioneering efforts involve capturing asteroids and comets to extract their resources for use on Earth. Among the inhabitants of one such asteroid named Tortatis is Nanbu Ushiwaka, a 12-year-old who holds the distinction of being the only child born in space to survive. Unfortunately, survival is no longer a certain guarantee. When a military satellite triggers a disaster during an operation to capture Halley's Comet, Ushiwaka and his fellow colonists are abandoned by both their country and company. Left to their own devices, they must figure out how to stay alive. The biggest threat comes from the nuclear reactor on the asteroid, which poses the risk of a meltdown. Will they succeed in escaping before it's too late, or will they meet their demise among the stars?