As he runs through the forest, Gyuhwan, who is a target of bullying, comes across a shotgun and some ammunition that belonged to his tormentors. Despite the risk, he keeps hold of the weapon, as he hopes to use it for his own protection. But things take an unexpected turn when he stumbles upon his classmates being attacked by brain-eating monsters. With the shotgun in hand, Gyuhwan becomes the sole barrier that stands between his fellow students and a horrifying fate.