Sunline Long Cast Fluorocarbon Tapered clear lines are wonderfully casting lines. They are similar to a Western fly rod knotless tapered leader except, this line is 8 meters long! You can cut it to length for any of your tenkara rods. There are two "gauges" of line, a #4.5 and a 3.5 which corresponds with the weight of Level Line.
These lines are clear and stealthy. If you are used to colored lines, nothing to see here, move along. But if you are already using or transitioning to a clear line system, and you want a line that casts nicely, then this is a line for you to consider. It won't cast for you or make you a better caster, what it will do is enhance the skill and technique in your cast as the tip of the line is tapered and will smoothly deliver the energy in your cast to your fly or kebari.
If you are a Western Fly Fisher transitioning to tenkara, then this may be your line as you already have used knotless clear leaders, and this is just an extension of that type of line end.
I like a stealthy long level line made of clear premium fluorocarbon however, this line promotes accuracy a little more than level line as it delivers the energy at the end of the cast better. I also like the performance in manipulation as the smaller tip transitions away from the larger level section farther than a level line to tippet.
I initially found out about this line from Chris Stewart but he no longer carries the line, Keiichi at TenkaraYa can get it for you no problem.
I use this line and it works very well.
I recommend it for those of you who want to improve your tenkara and you are already at an advanced level.