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 late-nineteenth century England, one year and three months after the dramatic conclusion of the original series, Kuroshitsuji II introduces a new butler and young master. The sadistic yet cheerful Alois Trancy has faced some harsh times. He was kidnapped as a baby, and was forced to work in a village as a slave. Gradually, he lost his parents, his best friend, and everyone he knew. Alois eventually returned home and became the head of his mansion, but seemed to exhibit some strange behavior ever since. Even more curiously, he returned with Claude Faustus, an enigmatic, emotionless butler with unfathomable talent...

Ciel and his butler, Sebastian, are asked by her Majesty to investigate the mysterious disappearance of small children and they are pointed in the direction of a traveling circus which's arrival to town coincides with the disappearances of the kids.

At the request of Queen Victoria, Earl Ciel Phantomhive goes to Weston College—a prestigious public academy for boys, known for its traditions and outstanding curriculum—to search for a relative of hers who has not returned home in months. Thanks to his noble status, the 13-year-old Ciel is swiftly able to enroll as a student, while his devilish butler Sebastian Michaelis assumes a teaching position at the school. Ciel does not anticipate being unable to locate the Queen's relative on campus. To make matters worse, he cannot request a meeting with the headmaster of the college, who may be the only person that knows anything pertaining to the disappearance. The only ones in frequent contact with the headmaster are the heads of the college dormitories, known as the Prefect 4 (P4): Edgar Redmond, Lawrence Bluewer, Herman Greenhill, and Gregory Violet.

19th-century England―Sebastian Michaelis, butler of the prestigious aristocratic Phantomhive family, and his 13-year-old master Ciel Phantomhive, the Queen's Watchdog, undertake dirty jobs in the underworld. On the Queen's order, Sebastian and Ciel head to Germany to investigate a series of mysterious deaths. While they search for the truth about the Werewolves' Forest where anyone who sets foot inside it is cursed to death, a horrifying curse falls upon them.