In the near future, the accidental release of an experimental virus causes an outbreak that changes the brain chemistry of every person in the world, allowing them to perceive extra-dimensional beings called "phantoms". In addition, some children born after the outbreak have developed special powers that allow them to battle and seal phantoms. Even though the vast majority of phantoms are harmless, many of these gifted children are placed in clubs and organizations dedicated to dealing with phantoms that prove to be nuisances or threats to humanity. The story revolves around Haruhiko Ichijo and his friends in the Phantom-hunting club of Hosea Academy, a private school for children with special abilities to seal phantoms, and their everyday life and struggles, dealing with phantoms.