A kid spent ten years alone with his robot learning to save the world. He comes home to find it already dead. The real story isn't about fighting monsters anymore, it's about whether Tetsuo's still a person after a decade of being treated like a weapon, and whether that matters when everyone he knew is gone.

Tetsuo is a shy boy whose only companion is Yukio, a giant robot. When enormous beasts from beyond the galaxy attack Earth, the pair become its saviors and fight the invading swarm alongside the Earth Defense Force. In the final battle Yukio is destroyed, and Tetsuo survives in an escape pod that carries him through years of cold sleep. When the pod finally lands back on Earth, he steps out into a ruined world buried under snow and ice, a deadly frozen planet. What became of humanity, and how did Earth freeze over? Tetsuo must also find out whether he can keep the last promise he made to Yukio. This is a science fiction mecha action series.