Humanity... a species whose thirst for power can never be quenched easily, attracted a foreign body to themselves called the Sydrols, an alien species which reduced the population to a tenth of its original number and set monsters on the loose to make the world inhabitable for their kind while they went off exploring more planets. Though these are difficult times, humans won't reside in hiding forever. The Hydras are large mechas, made from the monsters, to kill the monsters. This is the story of how Zoro Kakumushi and Lafina Larfi plan to take the surface back from the monsters along with many other allies. Our Final Salvation...