In a world powered by advanced technology, crime and action sweep through the archipelagic nation of cremona. Chief among the major players is “Killer B” — a serial killer who has thrown the city into chaos. The stories of Koku, the protagonist, Keith, a legendary investigator of the Royal Investigation Service, and a mysterious criminal organization intertwine on the path to reach their objectives.

When Keith is abducted and a friend from Koku’s past resurfaces, Killer B returns and everyone is pulled into a conspiracy involving the crown.