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The headmaster (校長, Kōchō) is the foremost director of Weston College. His decisions are regarded as absolute; they are, thus, peremptory, and preclude any objections. He has distinct rights, such as appointing members to comprise the P4, so that they may assist in governing the school, selecting which of the four dormitories students will be enrolled in as well as consenting to the transfer of a particular student from a particular dorm to another.
In the year 1889, when Ciel Phantomhive enrolls into Weston College, the real headmaster is on a trip around the world and will not return until next fall. Undertaker then takes the opportunity to usurp his position.
When Undertaker disguises himself as the headmaster, he conceals a substantial amount of his face with a cylinder hat. He dresses in a black, sophisticated suit and dons white gloves.
The headmaster is a very enigmatic and unfathomable individual; his background and motives are shrouded in mystery. Nevertheless, many students regard him highly; he wields great authority in Weston College, to which no one dares to defy or admit to debate his decisions. Exceptionally taciturn, he is inclined to silence and allows Johann Agares to speak for him.
The headmaster's formidable, abnormal speed rivals Sebastian Michaelis', which brings into question his species. His level of agility is phenomenal, and he is keen at detecting when others, such as Sebastian, are in pursuit of him. This is later explained by the fact that the headmaster is really Undertaker himself, who is a Grim Reaper; it is unknown if these personality attributes also apply to the original headmaster.
Public School Arc
On June 4th, news quickly spread that the headmaster has personally attended the annual cricket tournament of Weston College. When Sebastian Michaelis chases after him, however, the headmaster eludes him with relative ease by maneuvering to different areas.
At an elaborate staircase, Sebastian observes that the headmaster is purposefully evading him, and concludes that since the headmaster has already noticed his presence there is no need to hold back. He attempts to grab the headmaster, but only manages to grasp his coat; the headmaster has disappeared.
Later, the headmaster invites Ciel Phantomhive to his Midnight Tea Party. Ciel tells him about his concern with the puzzling disappearances of Derrick Arden and a handful of other students. He explains that the sudden transfer from Red House to Purple House, along with Gregory Violet's report that the students are all safe even when Derrick was not accounted for, troubles him deeply. He requests for the headmaster to call Scotland Yard. The headmaster does not respond; Johann Agares speaks on his behalf, claiming that all the students Ciel mentioned are present. Derrick Arden, then, joins the Midnight Tea Party.
To the surprise of Ciel and the prefects, Derrick suddenly attacks Herman, biting his arm. Ciel recognizes him as a Bizarre Doll; these creatures have previously wreaked havoc on Campania. He then removes his eyepatch and calls Sebastian, who appears immediately and wraps Derrick in the tablecloth. Sebastian also tends to the wound on Herman Greenhill's arm. Ciel reveals that Sebastian is his butler and that he has entered the school with the intent of solving the mystery behind the disappearances of Derrick and the others.
Ciel pulls a revolver on the headmaster, demanding an explanation. The P4 come forward and confess that they were the ones who murdered Derrick and made a contract with the Aurora Society, in an attempt to protect their school. They claim that the headmaster was not involved. However, Sebastian interjects that he was, in fact, the one who orchestrated the entire incident. At the protests of the P4, Sebastian adds that he never said the headmaster was the one behind it—he has emphasized "you," as in the individual referred to as the headmaster seated at the head of the table. After Sebastian suggests to the headmaster that they both drop the teacher act, the headmaster removes his hat and reveals himself to be Undertaker. Undertaker manages to evade capture and successfully escapes.