Cosmo-ui Miro

The explosion at the Geonyang chemical plant 19 years ago was not an industrial disaster. There was a secret experiment to awaken 'it' that had been sleeping underground in the city, and dangerous particles that had been dormant for hundreds of millions of years spread throughout the city through factory chimneys. A city that died in a disaster, but people still lived and children were born. The 'things' that were released to the ground in the past also coexist in the darkness of the city. The summer of 1999, when the children born the year after the accident turned 18! Once again, the secret in the darkness is about to awaken... In 1999, various mysterious events occur in a village at the turn of the century. Fearless girls and children who investigate the case, and various unidentified monsters. On the contrary, the adults who try to cover up the incident and 'it', the source of everything, are revealed!

(Source: KakaoPage, translated)

Note: Chapter count includes a prologue.