Joker first appears in the Circus Arc in Kuroshitsuji, and is part of Noah’s Ark Circus which is suspected in the case of the missing children.
Joker first appears to be the Ringleader in the Noah's Arks Circus, but is later revealed that he is more like "a hired shop keeper", but most of the carnies still refer to him as the boss as he directs the main show in the circus. He also has one of his hands missing for an unknown reason in his youth and is replaced with a prosthetic hand made by the Circus doctor.
