The Seventh Republic — the city despised by the sun. A nation which has not seen sunlight since the last great war, teeming with hidden and vicious criminals. Detective Hiryuu Ruka of the 13th Division, the Sideliners, has been pursuing the Cult Massacre case on his own — until his problematic behaviors get him reassigned to the Traffic Division. To return to the front line, Ruka takes on the challenges imposed on him. Meanwhile, a fire breaks out at the building belonging to a certain conglomerate, marking the tumultuous beginning that would shake the Seventh Republic.