Once Chibiusa returned to the future with Sailor Moon, Wiseman captured her and twisted her memories of her family in order to make her do as he wishes. Lonely and full of guilt, Chibiusa was infected with the Black Crystal and grew older, donning the earrings and crescent of the Black Moon Clan. She went so far as to seduce her future father, Chiba Mamoru, and attempted to destroy the Senshi for their insensitivity towards her.
Beautiful cosplay! I love the photography on this and such an awesome wig! Great work! Thanks to Ingrid for the email!
EDIT: Thanks to anon for letting me know this is Neko-Tin from Deviant Art!