As his name suggests, Undertaker is an eccentric funeral director and Ciel Phantomhive's informant who prefers to be paid, not by money, but by a good laugh for any information he might have. At first, it seems that only a select few (Sebastian being one of them) could get him to laugh, but recently, a detective made him laugh by merely introducing himself.
Why that is, no one knows yet.
This is a wonderfully convincing cosplay of the Undertaker! It would be interesting to see this cosplayer in person. Great work!