((Here's my idea for the story. If it's trash, feel free to tell me [no hard feelings] and I can try to come up with a better story if several people dislike the idea))
For as long as humanity has existed, so have monsters. Creatures of evil, who take on the form of man to wander about society. In this form, they're harmless. But it's their true form that is evil. These monsters wish for nothing more than death. Something about it elates them. Something in their genes. And when their thirst for blood is at its highest, destruction is sure to ensue. Fortunately, however, these monsters do not appear constantly. In fact, it has been so long since any of them existed that their existence is just a myth. They do, after all, only appear once every few hundred years, and the recounts from that time are often seeing as tall tales. But, in recent months, these embodiments of cruelty have returned and resurfaces to once again terrify the residents of the earth. And once again, there are forces who are here to stop them. There are humans with specialties that allow them the strength to fight back. Their genes have for years been dormant, but now that they're back, these sleeping warriors have underwent many new, strange, and impossible things. When they are attacked by the monsters and their adrenaline kicks in, their dormant genes become active and they transform into soldiers capable of taking down these creatures.