Years ago, after “the Gate” that connected the real world with the monster world opened, some of the ordinary, everyday people around the world began to receive the power to hunt monsters within the Gate. And so humanity was able to fight back against monsters, now seeing these people with powers as the heroes who fought for the good of the world.

 These people will now be known as “Hunters”.

 Ajin Genku, born without any abilities in a world where humans with superpowers dominate. Having no skills whatsoever to display, he became a laughingstock for all people around him.

 Until one day he suffers a serious accident.

 While he was on the verge of death, an unknown system awakens and declares him to be the descendant of a "King", completely changing his life and becoming a new person.

 Wielding the power of a "King", Ajin begins his path to become the Earth's strongest Hunter!