Monster x Monster

is a Japanese manga series written and illustrated by Nikiichi Tobita.

Plot
Once upon a time, this world was ruled by beasts. Human no longer sit on top of the food-chain, they are the monsters' prey. However, those who would stand up against the monsters gathered together and they continued to battle against the monsters in order to survive against their rule. Since then, hundreds of years have passed... and now the "fight" against the monsters has become the "hunt" for the monsters.