The former boss of the Gesso Family, Byakuran is the incumbent leader of the Millefiore Famiy. He wishes to obtain ultimate power by gathering the Vongola Rings, Mare Rings, and Arcobaleno Pacifiers together in one place. His assassination of both the Vongola and Arcobaleno Families including their friends and allies prove that he will stop at nothing to achieve his goals. Yet despite his ruthlessness towards his enemies, he maintains a carefree nature towards his subordinates.
Pretty cool cosplay of Byakuran! It kinda makes me hungry for marshmallows now. Thanks to Namine for sending this in!
EDIT: Thanks to anon for adding the link to the cosplayer schOki's website!