Nadia is a dead girl who is Dark and Kid's little sister. Dark stole her away from Orbkiller's protection to attempt to save her himself, which Kid says is futile and only causes her pain. She was lying dead and asleep in the Morgue until Fuuka woke her.
According to Dark, she "went to the doctor but didn't get better," and now she's always bleeding. Dark says that she is "sleeping" because she was hurt and needs to stay "D-E-A-D." However, Kid reveals that she was apparently killed by their mother before she abandoned them.
Nadia is a young girl with blond hair who lies dead on a gurney in the Morgue. She seems to have a typical autopsy's "Y" incision that seeps blood.