· Surface world: In the parallel time and space of 2025, the technological level is similar to reality, but there are inner worlds composed of "Evolvers" lurking underground in major cities around the world (such as "River City").
· Rules of the other world: The existence of superpowers is an "open secret". The government has established agencies such as the "Paranormal Phenomenon Administration (Abnormality Administration)" for vague control to maintain the fragile balance between ordinary people and superpowers. All major forces (officials, chaebols, civil organizations, criminal groups) compete here.
