Speaking about the move, Sunu told Arsenal.com that he was looking forward to more regular action during his time with Derby.
"I spoke with Arsène Wenger and he told me it would be a good thing to go out on loan," said the Frenchman. "I think Derby is a good club to go to.
"To play week-in, week-out is a very important part of football. In my first season I had the chance to do that with the Under-18s but since then I haven't played as often as that.
"The Reserve League doesn't have as many games and the Championship is more physical. It will give me the chance to work on my crossing and my finishing."