In Victorian-era London, on the night of Ciel Phantomhive's tenth birthday a fire destroyed his manor and killed both of his parents. In a moment of death Ceil strikes a deal with a demon, his soul in exchange for revenge. This demon becomes his butler and calls himself by name of Sebastian Michaelis, to protect and serve Ciel until the deal has been completed. One month after the fire Ciel returns from being missing, with his new butler Sebastian. Ceil is now the head of the Phantomhive corporation, handling all business affairs as well as the work as the Queen of England’s guard dog and looking for his parents murders.
In the crime-ridden, mafia-governed city of Ergastulum, Worick and Nicolas are two "handymen" known as "Benriya" who would take any dirty job from either police or mafia -- for a good price. After an assignment from police the two met and later joined by Alex, a former prostitute who got interested in the mysterious background of the team, in particular of Nicolas' abilities.
"Minimum" - a special inborn power found in a limited number of human beings, known as "minimum holders." In Yokohama, the detective team Hamatora, formed by two minimum holders named Nice and Murasaki, comes across information connected to a serial killer being pursued by their old friend Art. It turns out all the victims are minimum holders like them. Unwillingly at first, the two detectives become involved in the investigation.