In the early 21st century, the emergence of an incurable condition known as B-cell growth led some of the affected to become "Sleepers" - people put under stasis until a cure could be found. Yuji Kaido is one such Sleeper who awakens, several decades later, to a horrifying new reality. Giant bugs known as Blue have invaded the Earth, eating everything - and everyone - in sight. Now, all Yuji can do is escape from the city with the ones who saved him from his inevitable death, and make their way towards Second Earth: mankind's new home in space.