Kuroshitsuji / Black Butler

Kuroshitsuji / Black Butler takes place during the Victorian Era in England. The primary storyline of the anime/manga takes place from the perspective of Ciel Phantomhive, the last remaining member of the Phantomhive house. Ciel Phantomhive's family was killed by a mysterious cult, which resulted in Ciel making a pact with the demon Sebastian. In return for Ciel's soul, Sebastian would help Ciel avenge his family, through whatever methods of revenge were needed. Sebastian re-built his home that the cult burned to the ground, allowing Ciel to undertake his family duty while on his path for revenge.

 

Ciel's family serves the Queen of England, as the leader(s) of the Criminal Underworld, this ensures that the underworld maintained order. It earned the Phantomhives the title and nickname "the Queen's Guard Dog's", as they were expected to maintain order and handle any situation that would arise that would be affecting the public of England. Throughout the general story, Ciel Phantomhive encounters another family that served under the queen, the Trancy House. The Trancy House also served the Queen in the criminal underworld, being known as the "Spiders" of the underworld. Both Ciel and Alois have entirely different agendas, but ultimately both boys have made pacts with demons for revenge... both of their pathes to achieve such things are leading them both against one another.