The story follows Luck, the strongest sorcerer of the hero’s party, during a desperate battle against the demon king and his hordes. After their party manages to wound and drive back the demon king, they are immediately set upon by a massive army of demons. Facing certain annihilation, Luck makes the decision to hold the line alone, telling his comrades, the hero Erik and the warrior Goran, to escape while he covers their retreat.

What Luck expects to be a final, noble sacrifice turns into an endurance of legendary proportions. For ten years, he fights without rest, using a marionette spell to force his body to continue fighting even while asleep. He defeats wave after wave of demons, learns and reverses a demon commander’s life-draining attack to replenish his own energy, and eventually confronts and vanquishes the demon king himself. Upon emerging from the dimensional rift where the battle took place, Luck discovers that a decade has passed in the outside world. His body has also regressed in age, now appearing as a young teenager. His comrades, who believed him dead, have become heroes in their own right, with Erik ascending to the throne as king and Goran becoming the powerful guild master of the adventurer’s guild. A massive statue has even been erected in the city square to honor Luck as a legendary hero.

Overwhelmed by his new reality and desiring nothing more than a peaceful, laid-back life, Luck decides to hide his true identity. He adopts the alias Lock and registers as a novice F-rank adventurer, hoping to start over from the bottom. His plans for a quiet life are immediately complicated. His former comrades recognize him, and despite his protests, they are determined to honor him. He also finds himself unable to ignore those in need. He reluctantly takes on new companions, including a young wolf-girl named Sia, a talented warrior he rescues from a vampire, and Celliss, the daughter of his old friend Goran, who is a skilled but somewhat naive adventurer. Despite his best efforts to live as an ordinary rookie, Luck’s overwhelming power, honed over a decade of solitary combat, continually reveals itself, forcing him to navigate the gap between his desire for anonymity and his status as a living legend in a world he no longer quite recognizes.