Tetsuo, a shy boy, has only one friend: the giant robot Yukio. Together, they were humanity’s saviors, battling the galactic monsters that attacked from space.
Ten years have passed since the final battle that decided the fate of mankind. When Tetsuo finally returns to Earth, he finds it buried beneath snow and ice—a frozen world known as Snowball Earth.
Amidst the transformed landscape, Tetsuo clutches the promise he made to Yukio and begins his journey into the unknown.