His Butler, in Disguise (その執事、偽装, Sono Shitsuji, Gisō) is the forty-eighth episode of the Kuroshitsuji anime, and the second episode of Kuroshitsuji: Public School Arc.
Summary[]

Housemaster Michaelis teaches a class.
Sebastian explains his duties as a housemaster at Weston College: Each dormitory house at Weston College employs a small staff; out of them, the housemaster is the only educator. In the mornings, he brings his students to the schoolhouse for lessons. In the evenings, he returns with them to the dorm where he assists them with homework during his free time.
Although being a housemaster is demanding enough, Ciel also orders Sebastian to do his fag work for Clayton for him; this includes organizing Clayton's bookshelves, sewing on missing buttons, and preparing desserts for both Clayton and Ciel. While Sebastian finds this greatly bothersome, he cannot refuse an order and diligently fulfills his tasks.
Later, in the classroom, McMillan points out that it must be horrid for Ciel to do so many errands because Clayton exploits the fact that Ciel is not someone's fag yet. Ciel tells him that he has a "trick" for getting things done quickly which astonishes McMillan; he needs the entirety of Fag Time to sew on a single button and would love to know Ciel's "trick."
McMillan then notes that Ciel is not only adept at housework but at academics too as he got high marks on the latest test. Because of that, all senior students are talking about who will take Ciel as his fag. McMillan is certain that it will be Clayton which satisfies Ciel.

Swan Gazebo
At Swan Gazebo, the P4 and their fags have gathered. They discuss Ciel who has been standing out with his skills. On Edgar's request, Clayton comments that Ciel is highly gifted, undertaking all his tasks quickly as well as precisely. Further, although he is an earl, his teas could pass as the work of an elite French chef; Ciel told Clayton that it is his "hobby."
This stuns the others, and Gregory calls Ciel an "eccentric" and muses whether that is why he went to the Violet Wolf dormitory a while ago. The prefects become suspicious at this revelation, though Edgar swiftly stirs the conversation away by lamenting that he wished Ciel had been assigned to his house. After all, he is already the head of a prestigious earldom despite his young age.
Hearing this, Edward Midford asks for permission to speak. After Herman grants it, Edward informs the others that Ciel is his cousin and his younger sister Elizabeth's fiancé. He also tells them that Ciel was with him aboard the Campania which piques Edgar's interest. He wants Ciel to tell him the story. Edgar's fag Maurice Cole, however, wonders if Ciel might feel nervous getting invited to visit a group of older students. Edward then states that he thinks it is a good idea to invite Ciel; he might be harsh to him as he is family, but he respects him as his man for his accomplishments nevertheless. Following Edward's recommendation, everyone agrees to invite Ciel to Swan Gazebo at two o'clock tomorrow. Maurice volunteers to tell Ciel and leaves to find him.

Ciel grins, believing he received a chance to get closer to the P4.
Ciel is in the classroom talking with McMillan when another of his classmates arrives and informs him that Maurice Cole, Edgar's fag and the prettiest boy at Weston College, wishes to speak to him. Afterward, Ciel goes to meet Maurice who tells him that the prefects invited him to Swan Gazebo at four o'clock tomorrow. Ciel immediately accepts the invitation. As soon as Maurice is gone, McMillan and the other Sapphire Owl students surround Ciel and congratulate him for the invitation.

Ciel declares war on Maurice for thwarting his plans.
That night, Ciel meets Sebastian in his office, pretending that he is there to ask for help with his homework. Ciel tells Sebastian about his invitation to Swan Gazebo, though Sebastian already knows about it, and adds that they need to make sure that the P4 and their fags take a liking to him. Sebastian proposes to bring them tea and sweets, and Ciel orders him to make sweats that will "astound the prefects." Shortly afterward, another student knocks on the door to ask for Sebastian's help, and Ciel leaves Sebastian's office.
The next day, Ciel heads to Swan Gazebo alone, as Sebastian is preoccupied with his housemaster duties. However, when he arrives at the gathering place, the prefects and their fags are furious at Ciel as he is two hours late. Ciel tries to explain himself, but Maurice lies that he definitely told Ciel the correct time, and Edward tells Ciel to leave, as he betrayed his and his seniors' expectations.
When Ciel later meets up with Sebastian, he angrily tells him what happened. He will not simply let go of the matter though; instead, he sets out to take revenge on Maurice. Ciel is sure that Maurice must be a pathological liar because his hands are smooths, whereas the hands of other fags tend to be rough from the work they do for their upperclassmen. He adds that he could "easily" verify that Maurice lied, but because he does not want to let Maurice off so "lightly," he tasks Sebastian with finding other students that he has set up like that.
The next day, the Blue House students shun Ciel for breaking an appointment with the P4. This makes Ciel understand the P4's influence better, and he realizes that it will be difficult to find anyone who would testify for him under these circumstances.

Maurice, agreeing to make Edgar the dessert of his choice.
Meanwhile, Sebastian stalks Maurice throughout the schoolhouse and catches him receiving documents from some first-year student. Edgar asked Maurice for that data beforehand, and when Maurice brings it to Edgar, he pretends he collected it on his own. Ciel also follows Maurice around, though only as far as the Red House dormitory's entrance which is flanked by guards. Later, Sebastian himself in the lake by the Swan Gazebo and hears that Maurice prepared lemon myrtle soufflé glacé for Edgar.
In the afternoon, Ciel keeps an eye on Maurice while he and other Red House students have cricket practice. Concurrently, Sebastian approaches Joanne Harcourt in the library and helps him get Wissenschaft der Logik. After Sebastian praises him for being able to read Hegel's work in the original German and remarks that he must surely be popular because of that, Joanne tears up.
In the confessional, Joanne admits that he was once invited to Swan Gazebo but did not go as he never received the invitation. Maurice was meant to deliver it and he swore that he gave it to Joanne. When Joanne's desk was searched, an invitation was found, and Joanne's reputation was ruined from then on. Sebastian says that he believes him and tells him that all will be well.
In the evening, Ciel and Sebastian meet up to report their findings. Sebastian says he found four other victims of Maurice's. He also doubts that he does most of his fag duties on his own, e.g., the dessert "he" made for Edgar today is impossible to do within a day's Fag Time as it has to chill for several hours.

Soma arrives at Weston College.
Ciel then notes that it would be beneficial if they had a "pawn" at Scarlet Fox who could surveil Maurice more easily. However, because the headmaster decides the house assignments, they would need someone of high birth who would be guaranteed a place at Red House, even without a vacancy. Immediately, Sebastian and Ciel think of the same person. Although Ciel would rather not call him, he has no other choice but to do so.
Not long afterward, Soma Asman Kadar enrolls at Weston College, arriving on an elephant and eager to experience school life.