When fishing tenkara in off colored water, I've always found a white hackle kebari to be extremely productive. (I know, I know...the fly doesn't matter...whatever...)
I'm not sure if it's because the fish can see the fly better in stained water, or if it's because I can see the fly better (to manipulate it) in the dirty water, but I always seem to catch more fish when using this fly.
There's nothing fancy about this fly, the pattern is pretty much as simple as it gets...I tied this one with a tan body, but regularly tie them in all kinds of colors.
Tie a few up yourself...would love to see pictures of your next catch!