The Royal Sakasa Kebari is "Kiwi" Kuhlow's creation. It is a cross between the classic Royal Coachman trout fly and a Japanese kebari. Tied in the "sakasa" style, the forward slanting hackle will wave back and forth with gentle pulses of the rod tip. It really does look to the fish like something that is alive and swimming.
The sakasa shape also acts like a parachute, resisting being pulled through the water. That allows you to keep your line a little tighter and more of your line off the water. A line held off the water is not subject to drag, so fishing a sakasa style fly will improve your presentation.