After the untimely death of their parents, Han Yujin and Han Yoohyun grew closer than most normal siblings, with Yujin single-handedly raising his younger brother. When gates to otherworldly dungeons begin to appear around the globe—subsequently bursting and releasing monsters upon humankind—the state of the world changes overnight, as does the brothers' relationship. While Yoohyun immediately awakens as a superpowered S-rank hunter that few can challenge, Yujin must go to extra lengths to achieve his own awakening. Even so, he is met with disappointment when his rank is revealed to be F, rendering him practically the same as a regular person.

Over the course of eight years, Yujin is unilaterally shut out of his brother's life as Yoohyun goes on to establish Haeyeon—one of Korea's greatest hunter guilds. When a terrible tragedy gives him the opportunity to have a wish granted, Yujin simply chooses to return to a happier time. Memories intact, Yujin's only thought is to reconcile with Yoohyun. He does not expect to undergo a second awakening and, what is more, possess different skills than before. Although he may still be an F-rank, Yujin is thankful just to be able to live peacefully with his brother. However, Yujin soon finds himself entangled with an ever-growing number of high-class individuals whom he is in a unique position to support.