After being ambushed by unidentified attackers, Junu Kim, the first SSS ranked genius hunter, is hurled ten years into the past. Unfortunately, his hunting expertise is obstructed, and he is forced to labor as a dungeon custodian to restore his skills. Though he is skeptical about his new position at first, Junu becomes increasingly committed and proficient in his work. He faces a variety of hurdles as he endeavors to recover his hunting abilities, such as hostile creatures and treacherous associates. Nonetheless, armed with his might and his knack for cleaning, Junu confronts each obstacle with confidence.