Solo Leveling is set in a world where portals connect humanity to a dimension filled with monsters and creatures. Hunters, individuals with special abilities, are tasked with protecting humanity from these otherworldly threats. The story follows Sung Jin-Woo, a low-ranked hunter who gains the ability to see an interface called the "System," which allows him to level up and grow stronger like a character in a video game.
The System, introduced to Jin-Woo, allows hunters to level up their skills and acquire new abilities by completing quests and defeating monsters. while other hunters are stuck to being at whatever level they awakened onto only Sung Jin Woo can level up.