Kuromi is a character from the My Melody universe.
She is My Melody's rival and doppelgänger,
and
manifests as a white rabbit or imp-like creature wearing a black jester's hat
with a pink skull on the front and a black
devil's tail.
The skull's facial expression on her forehead changes to match Kuromi's mood.
Fittingly, her birthday is
on Halloween (October 31st).
Her name translates from Japanese to English as "black beauty".