The series occurs in 2030 when many people become cyborgs with prosthetic bodies. Primarily set in the fictional Japanese city of Niihama, Niihama Prefecture, the series follows the members of Public Security Section 9, a special operations task force made up of former military officers and police detectives. While the group investigates various crimes, both seasons feature ongoing investigations into two incidents that embroil the group in corruption within other branches of the Japanese government.