There is a guy in Japan, 松本, Matsumoto. Who has a blog, and he has also published a couple of kindle e-books. And I have also seen his kebari for sale on ebay.
The blog, the name on ebay, and the books all actually are under the name, Matsumoto · kebari workshop! or studio, [松本毛ばり工房！]
He makes a claim of quadrupling your catch rate, 釣果4倍！, by using his variation of
合わせテンカラ釣法！Awase Tenkara Fishing Method !
But, I have not yet been able to figure out just what it is.
His two e-books are also on Amazon US. They were only a couple of dollars. I purchased both of them about a year ago.
Each book is about 24 pages. There was no look inside feature. Turns out they are entirely text, no diagrams. A disappointment. However, I thought in trying to translate them I might learn more Japanese, and maybe learn something about his perspective on fishing too.
But it was a tedious work and I didn’t get very far. Before being distracted by other things.
Actually I had forgotten I had downloaded the kindle books until searching the internet for tips about detecting a strike. Prompted by this discussion, Which turned up his blog again.
The titles of his two kindle books are:
「飛騨川水系の目が疲れないから合わせテンカラ釣法と釣行記！」
and
「釣果4倍！目が疲れない！から合わせテンカラ釣法！」
I’ve never been satisfied I have translated the titles correctly.
However, both titles include the phrase , 合わせテンカラ釣法, Awase Tenkara Fishing Method. And I know Awase (合わせ) means connecting with the fish.
The first title also includes - Hida River System fishing record or fishing trip.
The phrase found in both titles, that I haven’t been able to translate is - 目が疲れない.
It either translates as - My eyes get tired, or My eyes are not tired. The ない ,nai bit on the end is usually something “is Not”. Similar to ません, masen, not.
But I doubt it should translate as eyes at all. Maybe as Sight. But I am not sure.
But
What catches my attention the most is the first part of the second title.
釣・果4倍！Fishing-fruit 4 times.
iow, Increase your fishing results 4x or quadrupedal your fishing results.
But how? What is he recommending?
On his blog he sometimes list the title differently.
As 「空ら合わせテンカラ釣法」“Something?” Awase Tenkara Fishng Method.
空ら often seems to mean, sky , air or even emptiness.
In another place as （空合わせテンカラ釣法) Empty? Awase Tenkara Fishing Method?
I do not know the difference in meaning of - 空合わせ, 空ら合わせ or から合わせ??
It is a fun mystery to try to figure out. 
Maybe they all mean the same thing only written differently.
I suspect he is advocating detecting takes by some motion of the rod tip, or possibly as, I think mentioned by Peder, detecting takes using the motion of the fishing line. As a long strike indicator.
I can read Japanese well enough to see that 片山悦二テンカラ名人から, (from tenkara master Katayama Etsuji) is mentioned. He seems to be providing input to part of the book. If you have seen his tenkara set up on the Daiwa website you might recall he uses a fairly long line, with a bright color marker, about 4 inches long, between the end of the level line and the tippet.
Now I am motivated to again try to translate the book. It might be a rewarding project.
Maybe I will learn some new strike detection method. Or just decide his claim is more boast than helpful advice.
Some relevant remarks found in his blog post (with my crude translation):
内容紹介 Introduction
ドライ毛鉤釣法から I switched from dry fly fishing method
「から合わせテンカラ釣法」に to awase tenkara fishing method.
転向して、釣果（釣れた魚の数）が、なぜ4倍になったかを述べました。
converting , fishing results, (number of fish caught) was quadrupled as I mentioned.
（空合わせテンカラ釣法）(Empty? alignment Tenkara Fishing Method)
毛鉤を振り込んで、remit the fly, (cast the fly, I think)
「ここらへんで・食いつくだろう」it will arrive here and be eaten?
というタイミングで 合わせる、by timing of awase
「空ら合わせテンカラ釣法」です。it is 空ら awase tenkara fishing method
毛鉤を目視しないので. because I do not look at the kebari
目が疲れません。my eyes/ my sighting does not get tired.
Links to two of his blog post about his recommended method.
1 Amago 1 Raibow trout 空 awase tenkara fishing method April 2017
Again it catches からawase tenkara fishing method Takehara River. May 2017
Hey, this kind of thing is how i keep my life in balance…
After hours doing things the easy way - it must be balanced with some time doing things the hard way. Stuff like this. 
Maybe some of our Japanese forum members can help, Letting us know if the Matsumoto · kebari studio advice is helpful or nothing new.