I Use a Mecha to Fight Zombies

A messy apocalypse, terrifying zombies, ferocious mutant beasts... The speed of human evolution is far unable to keep up with the speed of zombie mutation, and we can only rely on the power of mecha technology to support us. Finally, the invention of the time machine brought the dawn of hope to mankind, and mankind's last hope rested on the slowly thawing figure in the dormant chamber...