The beom are vicious tiger-like monsters who blend in with humans, brutally devour them, and bring chaos to the corrupt city of Sin-si. Four thousand years ago, they were sealed behind Beom Rock on Inwang Mountain; however, every year on January 16, the creatures escape and claim numerous victims. When the seal is lifted and the gate between their world and Sin-si opens, the beom swear to continue the war from four millennia before and destroy mankind.

Zeha is a lonely orphan filled with rage and resentment toward his parents who once abandoned him, and his caretakers avoid telling him about them. When a mysterious stranger offers him the truth he so seeks, Zeha jumps at the opportunity and finds himself trapped on Inwang, manipulated into becoming the one to break the seal and free the beom. Following the tragic event, Zeha regains his memories of the past and, faced with reality, vows to destroy the savage beasts.

Fate soon brings Zeha together with six other young men—Haru, Dogeon, Hwan, Hosu, Jooan, and Cein—to form a team called Chakho. Although the team is composed of drastically different members, they all grasp for the same goal: to hunt down and obliterate every last beom.