In Victorian London, the breathtaking performances of the Noah's Ark Circus have captured the attention of people all across the city. But the spell of magic and wonderment woven under the big top is not without consequences. Children have suddenly begun to vanish, and some suspect these mysterious performers are responsible. In an attempt to get to the bottom of these disturbing disappearances, the dashing duo of demon butler, Sebastian Michaelis, and his young master, Ciel Phantomhive, will infiltrate the circus and uncover whatever darkness may lie at its core!

Source: Crunchyroll

AniDB | ANN | MAL | TVDB | Wiki (en)

Prequel: Kuroshitsuji
Same characters: Kuroshitsuji II
Sequel: Kuroshitsuji: Book of Murder