Ten years ago, an unknown passageway known as "the Gate" appeared, bridging the gap between the real world and a realm of magic and monsters. Regular folks were granted with extraordinary powers and designated as "Hunters" to fight these malevolent creatures. Sung Jin-Woo, a 20-year-old Hunter dubbed the "World's Weakest" for his meager abilities, is among them. To pay for his mother's medical bills, he tirelessly hunts down monsters in Gates with lower levels.