In 2001, Takeru Shirogane awakes from a seeming nightmare where humanity enacted the Alternative V plan, which involved the evacuation of several hundred thousand colonists to another planet while leaving the rest of humanity behind to stage a last stand against the BETA. However, he realizes it was no dream, and instead a time loop has returned him to two months before Alternative V's execution. With his memories of the previous timeline, Takeru meets with scientist Yuuko Kouzuki at Yokohama Base...