Unidentified Object Filmed Over Yokohama, Japan

Here is an interesting video out of Yokohama, Japan that was supposedly shot earlier this month that shows a rotating object hovering in the sky. While some have posited that the object may be a balloon, I am not sure that is the answer. While a balloon would possibly tumble like the object in the clip after it was initially launched, a ballon it would eventually find equilibrium and steady itself – especially by the time it reached the apparent altitude that the UFO appears to be floating at. I thought it may be a kite, but there doesn’t appear to be any evidence that the object is tethered to anything. What do you think, is there a simple explanation for this mysterious object’s appearance over Yokohama or is it destined to remain a UFO?