A ARD for the M-22 might work and they will fit on a Leupold Mark 4 spotting scope. What are the outside dimensions of objective on the Kowa? The front of the Kowa looks larger.
I measured my Leupold and the outside diameter of the Kowa is probably too large to use the slip on Tenebraex covers. Too large for any screw in ARD's that I know of as well.