His Butler, Colluding
Ciel wins the P4's trust, but he still can't find a chance to get close to the Head Master. And so he brings up the subject of Derrick Arden with the P4 and their drudges. When he does, the expressions on the prefects' faces change...
Aired 04/05/2024EP 4 - His Butler, Colluding

Black Butler: Public School Arc
At the request of Queen Victoria, Earl Ciel Phantomhive goes to Weston College—a prestigious public academy for boys, known for its traditions and outstanding curriculum—to search for a relative of hers who has not returned home in months. Thanks to his noble status, the 13-year-old Ciel is swiftly able to enroll as a student, while his devilish butler Sebastian Michaelis assumes a teaching position at the school.
Ciel does not anticipate being unable to locate the Queen's relative on campus. To make matters worse, he cannot request a meeting with the headmaster of the college, who may be the only person that knows anything pertaining to the disappearance. The only ones in frequent contact with the headmaster are the heads of the college dormitories, known as the Prefect 4 (P4): Edgar Redmond, Lawrence Bluewer, Herman Greenhill, and Gregory Violet.
Ciel must concoct a plan to get in the P4's good graces if he wants to use their connections to succeed in his mission. But the distinguished college and its students hide much that is unseen, making this task more improbable than he could imagine.
(Source: MAL Rewrite)