One night, during a sacrificial ceremony to summon a demon, instead of forming a contract with the cult members, the demon states that he was summoned by Ciel, therefore he only agrees to form a contract with him, killing all the cultist members in the process. Ciel was also heat branded with a mark referred to as the "mark of the beast". Ciel then endures endless physical, mental and sexual abuse at the hands of his captors. The same night he is kidnapped by the attackers and then sold into slavery, where he ends up in the hands of a sadistic, demon-worshipping cult. Ciel, amidst the chaos, discovers his parents, Vincent and Rachel Phantomhive, to be dead along with the family dog, Sebastian. Taking place at the end of the 19th century, Kuroshitsuji follows these two as they face countless mysteries and dangers that plague England and threaten the Queen, uncovering the truth about what really happened to Ciel’s parents in the process.In Victorian-era London lives a thirteen-year-old earl named Ciel Phantomhive, who acquired this position after the events of Decem(Ciel's 10th birthday), when the Phantomhive manor was attacked by unidentified perpetrators and was set ablaze. But they soon begin to realize that it is foolish to meddle with Ciel and his demonic butler Sebastian.
At first, many perceive him only as a child surrounded by a few eccentric servants. After a tragedy leaves the Earl and his wife dead, many are shocked when their son, a young boy named Ciel, claims his place as the new Earl of the Phantomhive house.
Tucked away in the English countryside lies the ominous manor of the Phantomhives, a family which has established itself as the cold and ruthless “Queen’s Watchdog” as well as the head of London’s criminal underground.