This page may contain spoilers related to the Kuroshitsuji series, including information from chapters not yet released in tankōbon format. Read at your own risk!
- Main article: Phantomhive
Queen Victoria regularly assigns numerous cases to a certain individual, titled the Watchdog, that require investigating tasks to complete that deal with the Underground potentially harming the polite society. The current Watchdog is Ciel Phantomhive.
The assigned tasks are quite often rather difficult to accomplish and may necessitate the taking up of dirty methods by the Watchdog in order to simultaneously clear the current monarch's worries as well as to maintain the bridge between the Underground and surface world.
- Main article: Aristocrats of Evil
Jack the Ripper
Problem: It is the end of the social season in London when suddenly, a series of ghastly murders strike the town. The deceased victims are prostitutes, all of which suffered the same gruesome fate; namely, having their bodies cut open and their ovaries surgically removed. The criminal is dubbed Jack the Ripper by the police and other prostitutes due to the brutal nature of the crimes. Ciel Phantomhive is sent by the Queen to discover the true identity of the culprit.
Resolution: The true mastermind behind the attacks is discovered to be Angelina Dalles, with the Grim Reaper Grell Sutcliff as her accomplice. The killings cease to continue once the perpetrator is killed by the latter, who is taken away by William T. Spears from Ciel and his butler, Sebastian Michaelis, during their confrontation.
Problem: Ciel Phantomhive is sent to investigate a series of hangings where certain Anglo-Indians, after returning to England from India, have been assaulted, stripped and hung upside down from the eaves of the Hindustani Coffee House in Portman Square.
Resolution: The perpetrator of the attacks is disclosed to be Agni, who made a pact with Harold West Jeb in order to secure Mina's cooperation. In return, he would facilitate the elimination of prospective competitors for the Royal Warrant at the Curry Fair. The case is resolved when Ciel enters the competition and through Sebastian Michaelis wins the Royal Warrant. In the aftermath, Agni attempts to turn himself in to the Scotland Yard but is stopped from doing so by Sebastian.
Problem: Queen Victoria grows worried about the sudden disappearances of certain children in the middle of the night that mysteriously coincide with the arrival of the Noah's Ark Circus troupe at the respective towns they travelled to. She sadly compares them to the children who were kidnapped by the Pied Piper of Hamelin and requests Ciel Phantomhive to swiftly reunite them with their families.
Resolution: The Noah's Ark Circus first-string members are revealed to have been working for Baron Kelvin, who desired to lure Ciel to his mansion, after becoming enamored with him in a past encounter. He takes him to the basement, where he has replicated the room the cultists used with the intention of sacrificing Ciel and fervently asks for a reenactment. A traumatized Ciel promptly orders Sebastian to eliminate him, Joker and Doctor, as well as to burn the mansion down with the bewitched children still inside. Meanwhile, the Phantomhive servants eliminate the rest of the first-string members who were attempting to kidnap Ciel from his manor, unbeknownst to the fact that he wasn't there. William T. Spears, Grell Sutcliff and Ronald Knox collect the souls of the newly deceased.
Phantomhive Manor Banquet
Problem: Queen Victoria has found a certain "mischief" of Ciel Phantomhive's and decides to test him once again. Ciel then invites people to his manor for a banquet, where murders start to happen. The first to be pronounced as dead is Georg von Siemens, and the dinner guests begin a witch hunt-like hunt for the killer. Ciel is the one first suspected and the guests' patience is lessening because they are currently confined inside the manor because of a storm. Ciel, however, no longer becomes a suspect when the group find Sebastian Michaelis, his butler, stabbed to death by the fireplace the next morning, along with Patrick Phelps dead in Ciel's room. The case is up in airs until Jeremy Rathbone arrives and finds answers.
Resolution: Karl Woodley was named the culprit through careful investigation and the weather clears the next day, allowing the manor guests to leave. However, the professor, Arthur Conan Doyle finds it unnerving and returns to find that Vicar Jeremy is indeed Sebastian himself. He then proceeds to sit with Ciel for some tea as they explain the real murderer and the motives. Charles Grey was the one who supposedly murdered Siemens and Sebastian and this was all a ploy to stop Siemens' communication with Germany and frame Woodley because Woodley himself was guilty of a crime he was not detained for. Sebastian reveals to Arthur that he indeed is not human and he leaves the manor in fright. The killing that was not explained, Phelps' killing, was actually because of Snake. Snake decided to kill Ciel because he thought he was the cause of the Noah's Ark Circus other first string members' disappearance, but his snake ended up poisoning Phelps instead. Ciel ends with a lie that he is still searching for the Noah's Ark Circus members and has Snake join his house as a footman. Sebastian shows the servants he is alive by mysteriously "arising from the dead" when he rings his gravestone bell, causing the servants to dig him up and finding he is indeed alive.
Illegal Human Experimentation
Problem: Queen Victoria sends a message regarding human trafficking that is taking place in the cruise ship headed for the United States, the Campania. It is rumored that the trafficking is being headed by a cult that wants to reanimate the dead.
Resolution: The human trafficking was a farce. In reality, it was all a plan made by Undertaker as part of his own Bizarre Dolls experiment. The Bizarre Dolls escaped their confinements and attacked the crew and passengers. The survivors made it off alive, but the ship sank after crashing into an iceberg.
Derrick Arden's Disappearance
Problem: Queen Victoria is worried about her relative, Derrick Arden's wellbeing when he refuses to answer letters and return home for almost a year, despite his mother contacting the dormitory. Due to the fact that several other students are doing the same thing, Ciel Phantomhive is requested to investigate the reason for why the students are refusing to go home.
Resolution: Derrick's apparent disappearance is unveiled to be an accidental murder by Herman Greenhill, who killed him in outrage upon unearthing his bullying tendencies and fabrication of talents. The prefects are then compelled to also murder his duplicitous friends and Johann Agares, who were his accomplices in the scheme, in order to preserve tradition.  To cover up the crimes, the vice headmaster and Derrick are subsequently turned into Bizarre Dolls by Undertaker, with the latter impersonating the real headmaster. Undertaker manages to escape capture during the ensuing struggle with the bizarre dolls. Derrick and friends' scandal is buried with the cover story of a tragic boating accident and the prefects are expelled from Weston College as punishment.
Problem: Queen Victoria is concerned about a string of mysterious deaths that are occurring in southern Germany. Perfectly health bodies had become grotesquely deformed and the affected people died shortly afterwards. After the Kaiser and the German government refused her offer of assistance, she sends Ciel Phantomhive to uncover the cause of the incidents.
Resolution: The so-called curse was actually the result of German military scientists experimenting with poisonous gases. After killing all the scientists, the soldiers in charge of the program sent a panzer to eliminate the Phantomhive staff, but was it destroyed by Sebastian. Ciel had Sullivan and her butler live in England while Sebastian hid the gas samples they stole from the lab under a rock in the ocean.
Sphere Music Hall Gatherings
Problem: A recently popular music hall garners attention for holding enigmatic parties every Saturday in the evening, where masses of people seemingly intermingle with no regard for social classifications. Due to the large influx of attendees, the roads in front of the concert hall are increasingly blocked by numerous horse carts. Perplexed, Queen Victoria dispatches investigators to enquire into the gatherings but to no avail; peculiarly, they become regular attendees themselves. She relates to Ciel Phantomhive her concern of the possibility that "some manner of evil" may be taking place; whereupon the latter decides to discretely investigate the hall himself.
Resolution: Not yet achieved.