Mysterious black hands on chapter 383 of Hunter x Hunter On Hunter x Hunter chapter 383, something that looks like black hands suddenly appear and it took 1 princess life.


  


Is that a "Nen" or is it the Black Continent thing?
If you read the succeeding pages of that chapter, Fugetsu Hui Guo Rou clearly realizes what it was and said to herself that: 


  Leaving the ship...doesn't mean escape...but death?!


Also, after saving Kacho Hui Guo Rou, or her Nen beast to be exact, she told her that:


  There's punishment for leaving the ship.


This leads to the conclusion that it is probably a Nen ability or something similar, put in place around the ship to detect and prevent people leaving and eliminate them if they ever make it out. As to who put this up, it was never revealed if I recall correctly.