The future should have been a technological and advanced age as everyone expected, but not everything turned out as expected. These scientific and technological advances of human beings caused the awakening of some creatures under the ground. It turned out that there were creatures sleeping under the earth, in the ocean, waiting to wake up. On the first day that mankind learnt about the existence of those creatures, there was an earthquake; thanks to that earthquake, a creature of about 10 metres in size came out of its nest under the ground and terrorised mankind. Many people lost their lives, houses and buildings were destroyed.

They wanted to put an end to this chaos, and for this, a military unit was activated. They opened fire on the creature and won a victory that resulted in long efforts and many deaths. Thus, troops began to be formed to destroy the creatures that appeared.

Today there are 12 teams. Eleven of them are defence teams and one is a clean-up team. Only those who had undergone rigorous training and passed a military exam could join these teams. After the disaster about 10 years ago, something was learnt about those creatures. For example, they ranged in size from 5-25 metres and weighed several tonnes. S class creatures were the strongest, A class creatures were the toughest, B class creatures were the fastest and C class creatures were ordinary, in other words the weakest.