One-Cup Brewing with the Matsuya Method/松屋式一杯だし

Shukan Flavor No. 53 is about one-cup brewing with the Matsuya method.
週間フレーバーNo. 53は松屋式の一杯だしについてです。

Shukan Flavor No. 53/週間フレーバーNo. 53

Again, the Japanese version is omitted to save time.
時間節約のため和文は省略します。

At 2:27, Nakagawa-san says that with the Matsuya method, water control is everything.
It is difficult to do one-cup brewing with the Matsuya method, and Nakagawa-san will never teach you how to do it unless you have mastered five-cup brewing with the Matsuya method.
He first does five-cup brewing, using 50 g coarsely ground coffee (10 g per cup), to make "reference coffee". The idea is to approximate one-cup brewed coffee as closely to this reference coffee as possible by using all of three measures:
1. Use more coffee beans (15 g instead of 10 g),
2. Grind coffee beans more finely (7.5, for example, instead of 9 for Flavor Coffee's mill)
3. Pour water more thinly.
At 30:45, Nakagawa-san starts digging a hole.
At 33:25, he starts pouring water very thinly for murashi (steaming).
At 39:05, he starts pouring water for brewing. The water flow is very thin again. He makes sure that he doesn't pour water near the circumference.
At 40:00, he dilutes the coffee with just a small amount of water.
Despite the extra 5 g of coffee beans, the resultant coffee is slightly less strong than the reference coffee.
At 41:04, he shows one-cup brewed coffee (right) and the previously made reference coffee (left).
At around 41:40, he says that he has brewed nearly 100 cc coffee (instead of 120/2 = 60 cc). Otherwise, he couldn't get the (necessary) flavor.
On the one-cup brewing page
http://www.flavorcoffee.co.jp/fla-49.html
of Flavor Coffee's site, he writes:
Stop brewing when you get 50 to 70 cc coffee. (Determine this amount by yourself by trying as many times as necessary.)
(I think you can now imagine how difficult one-cup brewing with the Matsuya method is. It's difficult even for Nakagawa-san!)
At around 43:08, Nakagawa-san says that the two brews taste different, and "sadly", the reference coffee tastes better.
In response to a request, Nakagawa-san decides to do one-cup brewing with a very fine grind.
At 50:07, Sae-chan shows the coarse grind (grind level 9), usually used for 5-cup brewing.
At 50:22, she shows the fine grind (2).
At 52:06, Nakagawa-san starts pouring water for murashi.
At 52:52, he says he doesn't want to do one-cup brewing because it's tough to do.
At 53:43, he starts explaining the cautions when using a fine grind:
With such a fine grind, you can get strong coffee, but that also means that zatsumi (miscellaneous (unpleasant) flavors; off-flavors) will be extracted sooner. You have to determine when zatsumi start to be extracted. To do so, Nakagawa-san asks Sae-chan to taste coffee while he is brewing.
At 56:48, he starts pouring for brewing.
At 57:00, 57:05, and 57:10, he tells her to taste.
At 57:15, he says that astringency will start to emerge soon.
Sae-chan agrees, saying, "It doesn't taste good any more."
He stops brewing. The amount of coffee is less than 100 cc.
At 58:04, he explains in detail. In summary, with a finefind grind, one-cup brewing with the Matsuya method becomes even more difficult, and it's easier to brew coffee if you use a medium grind because you can delay the extraction of off-flavors.

***
As for me, I have never tried one-cup brewing with the Matsuya method. I'd rather use 5 g more coffee beans to do 2-cup brewing. Anyway, I haven't mastered the Matsuya method yet, and I'm not qualified to try one-cup brewing.
私自身は松屋式の一杯だしを試したことはありません。コーヒー豆をもう5 g使って、二杯だししたほうがいいと思います。ともかく、まだ松屋式をマスターしてないので、一杯だしを試す資格はないです。