The magical barrier protecting humanity in KPop Demon Hunters is called the Honmoon.
According to the film’s history, three women became demon hunters long ago and used their singing voices to create the Honmoon. Later generations of hunter trios continued maintaining it. The barrier separates the human world from demonic forces and is sustained through the hunters’ musical power.
The Honmoon is not the same as the Golden Honmoon. The Golden Honmoon is the stronger final form the hunters hope to create by strengthening the existing barrier. Its purpose is to permanently banish demons rather than merely hold them back.
This mythology gives HUNTR/X’s performances a practical purpose. Their concerts and songs are part of the defense system, so their careers are connected to the safety of humanity. The film’s central conflict grows when the demons attempt to weaken the Honmoon by manipulating public devotion.