The Japanese Ministry of Defense has an anti-paranormal special forces group called the Paranormal Disaster Countermeasure Headquarters. They're the ones responsible to protect Japanese soil and its people from supernatural and paranormal events. However, things didn't go so well in one of their missions, which leads to intervention by the Ministry of Enviroment's Supernatural Disaster Countermeasures Division after the PDCH has sustained large numbers of casualties battling demons.
"Mob" is a boy who will explode if his emotional capacity reaches 100%. This boy with psychic powers earned his nickname "Mob" because he does not stand out among other people. He keeps his psychic powers bottled up so he can live normally, but if his emotional level reaches 100, something will overwhelm his entire body.