Both. But if someone calls them then they're going to have a talk with you at the least and tell you not to use it in public. It's possible they may take it, but since it's clear that's pretty unlikely.
You're allowed to own even all black airsoft guns, but the police take brandishing a firearm in public very seriously and will consider a black airsoft gun, or even a clear one (depending on what you're doing with it) as the same as a real gun. So if you don't even have the privacy of a fence I'd advise against firing it in your backyard. Especially since with no fences, stray bbs could go anywhere.