I Am the Controller of Time!

A hundred years ago, changes occurred on the continent, and creatures appeared out of nowhere and wantonly destroyed the homeland where humans depended on for survival. People collectively called these creatures alien beasts. People had to move backward and establish united city-states to jointly resist the invasion of alien beasts. But the good times did not last long. With the addition of large and super-large alien beasts, the human city-state gradually began to collapse. But with the addition of a group of people who call themselves superpowers, the continent gradually began an era in which humans and alien beasts coexisted...