This is a tale of the battle between a group of heinous, modified criminals known as "Ganned" and the countermeasure team "SIGNAL" in the near future. Rikka Shirane, a genius scientist from "SIGNAL," was troubled by the reality of being barely able to cope with daily crime responses. At such a time, she learned news about high school students in a neighboring prefecture who had established a vigilante activity club. To guide them, develop their skills, and investigate suspicious individuals, Rikka decided to transfer to their school.