The Black Wings look like a huge white wall; the nature of the artwork is still uncertain, but its creator is pictured painting it. It is now chained and hidden in a secret location very few, including Satoshi Hiwatari, know.
In the anime, the Black Wings resemble a disfigured human skeleton hidden in a tall box similar to its manga counterpart. It has no right leg, but a stump with protruding spikes as its left leg. It wields a sword with a hexagonal hole near its tip, on its back, which is connected to the statues right eye through a cord running from its handle. It also has two large black wings on its back. Its skull is cracked for the time period that Dark and Krad are separated from it. That cracks disappears after Dark and Krad are sealed inside the artwork.
The Black Wings were supposed to be the Hikari family's greatest artwork. After years of work, and right before its creator gives it life, a member of the Niwa family appears to steal it. As the ritual is interrupted, the magic is parted between the two humans instead of entering the artwork, cursing them with Dark and Krad.
That curse was passed generations after generations in the Hikari and Niwa families. Whereas Krad makes his hosts' life shorter, Dark spoils the Niwa men's love stories.