It is a Japanese website
There is an interesting description about “郡上毛鉤 fishing”
I do not believe in the website of the fishing gear maker, but I can trust what is written here 
How to cast a line makes a circle around the rod tip
It does not involve large motion
It is the original tenkara casting method
ありがとうございます、todoroki san. I’ve read that webpage was really interesting.
Patchin, Patchin and whip-like Instead of shaking,
It is important to turn at points to draw a circle.
パッチンと・鞭のように [ Pacchin to muchi no yō ni]
I think パッチン (Pacchin) means, Snap. And casting with a circular motion is to prevent snapping the line. Whip like.
I find that an interesting statement. In Tenkara Angler Spring 2016 issue,page 46, is Part 2 of Rob Worthing’s series on advanced casting. Wherein long line casting (described as casting a line 2.5x rod length) the instructions are the sound: Swish (back cast) Swoosh (forward cast) No crack (ie Snap). And those were tips from Sakakibara Masami [ 榊原正巳 ]. It has been a while since I read it, but I don’t recall a recommendation to use a circular or round cast.
Tenkara Angler Spring 2016 issue
The Pesca mosca Valsesiana anglers in northern Italy use very circular cast. I always assumed it was done to avoid tangling the multiple flies they use. 4 or more. Rather than to avoid line snap.
You might also find Chris Stewart’s description interesting.
http://www.tenkarabum.com/pesca-mosca-valsesiana.html
It is also interesting that he writes - The trick of casting, Because the rod is heavy · Do not swing big,
Shake it small. [ " キャスティングのコツは、竿が重いため・大きく振らず、小さく振る。"]
On this website, it is also remarked that the Gujō pole of Fukute-san (福手さん) is heavy, [ " 持ってみると、重い・・・"]
ロッドフリフリとは? What is - Rod furifuri? A phrase used on the above website.
I think it is swinging the rod. Testing out the feel of the rod.
But, I’m not sure that is correct. I even found a blog with the same name [ロッドフリフリ｜リンのブログ。rod furifuri ｜Rin’s blog.] while trying to figure out what it means. 
It looks like the same 平田久信さん [Hirata Hisanobu-san] mentioned in the Fishing Cafe Vol. 57, also wrote about Gujō Tenkara [郡上テンカラ] in a Spring 1999, issue of Keiryū Tenkara Club mook.
別冊・渓流フィッシング第58号’
99渓流テンカラ倶楽部〔絶版〕
廣済堂出版・1999年4月1日発売。
tenkarakebari blog Gujō Tenkara 2012.05.07
However, it appears copies of the issue can be found from some shops.
rakuten 渓流テンカラ倶楽部 ’９９ / [ムック]
The 「ヒラタカゲロウ・隠し毛鉤」`hiratakagerou kakushi kebari’ , “Hirata Ephemera, hidden fly”
(note, I’m not sure if “hidden” is a correct translation)
Seems to be the Viper skin body kebari [マムシ胴・毛鉤. mamushi dō kebari] we have seen before.
But I am not sure this Hirata-san (平田さん) is the same person we have seen tie this kebari before. Or a different person also named Hirata-san. Because the name used is a little different.
「ヒラタカゲロウ・隠し毛鉤」vs 「ヒラタカゲロウ・毛鉤」, the 隠し, kakushi, hidden, part if left out.
tenkarakebari blog ヒラタカゲロウ毛鉤 2012.06.16
It mentions going to a Hirata Fishing Gear Shop [平田釣具店さんへ]. But I could not determine which one, there seems to be more than one.
Reference
平田・・・Hirata = Person’s name
ヒラタ・・Hirata = insect name
Both are the same in Roman letters
Translation is accurate
The question is in the article
Viper skin body kebari = Hirata Ephemera kebari
・・・This site is mistaken
The place to be used is also different
Although it is the skin of a viper snake, it is not on the surface and the correct answer uses the skin on the back side
The effective nature is the same as this オーロラ皮
It is a member of the Yoshida kebari group（吉田毛鉤）, but this group has many mistakes
Although it is a famous group, there is not much knowledge of “tenkara-kebari”
Viper kebari is a more detailed explanation of this blog
An odd material. Seems to be used a lot for Sabiki (サビキ). I am guessing the aurora name is because this material reflects a spectrum of light. Like scales. And attracts predator fish.
http://www.tigerbari.com/parts/z-101.html
But funny coincidence. The first time copied the name, I missed the last character for leather. Only copying オーロラ。which is oorora, Not aurora . But that is what an internet search found, pictures of the northern lights, aurora borealiis. Discussed in another forum thread.
Italian / Valsesiana style - Lenza in crine (fishing line in horse hair)
From digital translation of the video description:
In this video you see Arturo Pugno while he builds a piece of line in horsehair. As usual in Valsesian fly fishing, even the line is built only with hands without any tools and is a further example of how the talent combined with a remarkable manual ability, has allowed in the past and still today to get very practically with almost nothing.
A friend recently asked me how strong a 3 hair line is. All I could say at the time was to relay what Chris Stewart had said about the size of fish he had caught with 3 hair line. An interesting thing on the next website, he does a kind of test of line strength by lifting a 1kg weight with a 3 hair line. So at least 2.2lbs.
La pesca a mosca Valsesiana - equipment and line
On page 2 of this PDF document - Schema della lenza in crine valsesiana (Line diagram Valsesian horsehair fishing line) However, I think it would be a heavy line.
[from the first sentence - Fly fishing is an ancient and traditional method of fishing typical of the
Valsesia, still practiced: you need a fixed rod, a long line free of braided horsehair and a hook with a row of artificial flies.]
http://www.giannimolino.it/Documenti/La%20mosca%20valsesiana.pdf
As an aside, I think the flies in this 17 page document are very similar to tenkara kebari.
David san thank you for posting this video and document . It’s very interesting that there are three kebaris on the picture, the Lime made from 20 hairs to 2hairs should be heavy but might need such weight at Valsesiana.
Yesterday I completed making two 4.3m, 4-horse hair level lines. One for me & one for a friend. Each required 7 snoods.
Each snood was about 65 ~ 67 cm in length. So about 6cm / 2.5 inches was lost to knotting them together. Only a few hairs broke when stretching them before tying and twisting the snoods. Some broke near the ends, a few broke in the middle. It’s kind of amazing how sensitive your fingers are sensing the thickness of the horse hair. Some hairs clearly felt thicker than other hairs. And on some you can feel the taper in the hair, the tip ends being thinner that the top end, the newest growth, being thicker. I think if you wanted to take an extra step you could sort through the hairs and make your snooks only with thicker or thinner hairs.
I don’t think I’d want a line longer than this, maybe shorter, and it’s easier/quicker to shorten a line than make it longer.
I did not put any kind of adhesive on the knots, but I may go back and paint the knots with white Uni POSCA marker, the same type marker I used to make sighting marks on the end of the line. It may help the knots to hold yet remain flexible and not make a hard stiff point that might cause breakage. Posca markers are water based, light fast and water proof - I don’t think it will damage or weaken the horse hair.
Now I think it best to fish with them and see what adjustments I would want to make before making another one, or deciding it was just something fun to try, but it’s not for me.
David San. this line looks really nice! I hope l can read your comment about to fish with this fine line in near future! ありがとうございます。
@dwalker
Just by looking at photos, I feel the high quality
The uniform twist and the beauty of the perfect circle it produces
It is a wonderful work
@mangetu , @todoroki34 - ありがとうございますThank you. The line may look better made in the pictures than it does in my hand. But I hope they are twisted and knotted as well as they look in the picture.
I should get to fish with the lines before the end of the month If I get the chance to go to our vacation house where there are cold water fish, locally I have mostly warm water fish and they do not seem to active yet. And snow is predicted tonight or early tomorrow. Or maybe just rain. The weather report keeps changing.
Pretty impressive stuff.
Nice looking work and I really like the extents you have taken this.
Thanks, over the summer I will find out if it’s something I like or just something that was new and fun to play around with for a while.
Folks might be interested in the ebooks and video content on this subject that we’ve been working over the last month.
It is a combination of lessons, interviews and video demonstrations by Hisanobu Hirata from Gujo, Gifu prefecture - who for the last 20 years has been running the shop ‘Hirata Tsurigu’ (Hirata Fishing Gear) in Shiro-tori, Gifu prefecture. His shop is just over the mountain ridge from Itoshiro, where Shouichi Saitou established Catch and Release with habitat management as a pioneering method of fishery management in Japan.
Since swapping his career of professionally catching large amago for local inns in the manner of Shokuryoushi (as his father did), he has personally mentored 160 anglers in his methods of tenkara.
The content we’ve produced (over annual visits spanning four years) includes complete demonstrations (written, drawn, photographed and videoed) of his horsehair line making methods, his fly tying and his onstream casting techniques, line positioning, sasoi manipulations and fish catching examples.
He also explains about methods for hooking fish in different parts of the mouth as well as the back story to his development of his mamushi kebari patterns, plus how he decides on what colour of fly to use.
There’s a lot of info about changing tippet length and line anchoring to match how different types of fish take hold of your Kebari in order to get better hook up rates.
Of course there’s information on otsuri and accounting for it in how you design horsehair lines (plus the footage of us being shown the hand drawn diagram introducing the concept of otsuri for our first time)…
Plus the pace of water coverage and how the typical circular/push ‘shokuryoushi’ style of casting matches both the pace of fishing and the types of rods and lines generally preferred by anglers from that ‘school’ of fishing.
We hope to set up a free online screening window of the onstream component of that video so it can be seen, appreciated and shared widely - with an opportunity to buy the whole bundle of interviews, line making, fly tying videos plus the onstream video of course and supporting ebooks to keep forever for yourself if you like.
Yoroshiku onegaishimasu,
Paul
PS he starts out his line making lesson by explaining how to match a line design to the specific rod that you’re going to use it on.
Got home last evening after nine days in Pocahontas County. Didn’t get to do as much fishing as I had hoped. The river water level was high due to several days of rain before I arrived, and rain on several days while I was there. And one day was dedicated to mowing lawns, our own and our three neighbors lawns as they also had not been there since last fall. Finally the water level dropped enough I had a little more bank area to stand on and fish, and the water volume had dropped a bit.
Managed to catch a few brook trout which seem to come out of Leatherbark creek into the larger river in the spring. But caught them using FC LL. After that I switched to the 4-hair horse hair LL I had made. I liked the way it cast, I would still estimate it cast about like a #3.5 line. But never caught any fish with it. The water level was still high enough the open bank area was still limited. Maybe all the commotion from the previous fish caught may have sent the alarm to the fish to be more cautious or move to the opposite bank, I stopped seeing as many fish rising. There should be more opportunity to try out the horse hair line next trip. But I’m off to the N.C. outer banks tomorrow morning, probably 3 weeks or so before I get another opportunity to try out the two horse hair lines I made, one 4-hair the other a 3-hair line.
I’ve been meaning to do a user update about the two 4.3m horse hair lines I posted a picture of in April.
I sent one of them to a friend in Tennessee who mostly fishes lakes either from shore or in a kayak. He reported he liked the way the line cast and caught several moderate sized fish with it. But eventually it broke near the end after he hooked a carp and it managed to get under some tree branches that had fallen in the water. He said it broke in the middle of one of the last snood. So at least I was happy to learn that the failure was not a failure of my connecting knots. I had sent him a few extra horse hairs so he could get some experience twisting them into a line and repair it should the line break. I do not know if he has repaired it and fished with it some more.
The fishing is always good. The catching sometimes is not.
It has been an odd summer. At home very dry. The creek along the south edge of my lawn is almost dry. At a level I don’t usually see till late August. In contrast at the family vacation house four hours away it has been a wet summer. Rain every other day or two. I’ve missed several days of hiking and fishing due to rain or high fast water levels. And when I have been able to fish the catching has been sparse. I’ve almost convinced myself the high water levels have washed away a lot of the fish. In May I noticed evidence of flood levels higher than I have seen before, and at one place I frequently fish there is a high steep bank covered in huge stones the size of bushel baskets that have been in place ten years or more. Many of them have washed away. Many had slipped in May and more of them several feet farther down stream two weeks ago.
I was able to fish with the horse hair line several different days.
Mostly attached to a Suntech Tenkarabum 4 meter rod (nice rod, I like it. Good balance and nice caster. But like Tom Davis - I thought the grip has smaller diameter than I prefer. However, after getting used to it, the grip size is fine) The third day out I had some beginner’s luck, catching 3 native brook trout in the first ten minutes on the water. None of them were large fish, 8 ~10 inch fish. On following days I caught a few more fish of various species with it. Some smaller some a little larger. None over 12 inches. So I think a 4 hair line is good at least up to that size.
The line cast ok in moderate wind, handled the fish ok in somewhat fast water. And I had no line failures. Visibility was good. I can’t say the colored maker section I added was of much help or needed. I had no troubles with line tangles caused by the knotting of several snoods together to get the final length I wanted to make. It is a 4 hair level line that I feel cast about like a #3 (3号) LL. But it has a different feel to it compared to either soft or stiff FC LL. I liked the way it cast quite a bit. Before beginning to fish I would always lay the whole line in the water, believing a little water absorption may make the line more elastic, less brittle, and less likely to break. Oh, I might also note I had no individual hairs break.
A line making tip from Hirata-san in the Discover Tenkara materials Paul mentions above.
Check for and reject flat hairs
Hirata-san advises to only use horse hair that is round as otherwise it will not furl correctly and twist up as smoothly as it otherwise would. So reject any hairs that are flat in cross-section, they will feel bumpy when pinched and rolled between thumb and forefinger. That is advice I don’t recall reading about before.
I have not yet tried to make this test. But when I made my two lines I noticed my fingers were quite sensitive at noticing the difference in diameter of different tail hairs or even the difference in hair diameter along the length of individual hairs. This was noticed during the initial first stretching of the hair when selecting which hairs to twist, and which ones to reject because they broke. [ what can I say - having girly-man hands from no longer doing much hard manual labor that probably results in having more sensitive finger tips, ymmv] 
In fact after making a few snoods I made a conscious effort to make a few snoods only from hairs that all felt a little thicker than other hairs, and set those snoods aside to be used at that the top end of the line. The end that would be attached to the lillian. Reasoning that even if my intent was to make a 4 hair level line. The line would still have somewhat of a taper due to the top 3 or 4 snoods being made of 4 thicker hairs. The rest of my snoods I made from a mixture of thickness of hairs that had all passed the stretch test. All the hairs seemed to be thinner toward the tip of the hair. Therefore I tried to keep track of the thinner and thicker ends and before knotting them and twisting them I tried to balance the snood by having 2 hairs with thicker ends + 2 hairs with the thinner ends - at each end. Thereby hopefully being of near equal tensile strength along the full length of the snood.
Point is - if you want to make a horse hair line - after the initial hair strength stretch test to find and discard weak hairs - try and see if you can detect flat sections along the length of the horse hair, by rolling the hair between thumb and forefinger when selecting which hairs to use.
I might also note that Hirata-san did not wet the hairs. But I think that is a step I will continue to do.
After each snood was twisted and then coiled into water it was amazing to see little loops appear along the length of the snood as the hairs absorbed water and see the line untwist a little. These were all things I tried to smooth out and remove before knotting the snoods together. I guess maybe that is a step I could skip after twenty plus years of making horse hair lines. I’ll probably never get there.
I should be able to fish with it more soon, after returning to the vacation house. Maybe before then, but local streams are bushy, with to many places with tree limbs extending over half the stream width, and I’d prefer to not yet report on how the line does after a kebari gets stuck on a high tree limb.
This is where a horse hair line will shine.
