My teacher, Kiku Day, who is a student of Okuda Atsuya, the head of the Zensabo school, shot this video showing Kodama Hiroyuki explain how he makes jinashi shakuhachi. Kodama is also a student of Okuda, and I have a 2.0 jinashi made by him.
It is very interesting to see the process, both of boring and drilling the flute, and of tuning. One thing I note from the way he handles the instrument is that bamboo really isn’t fragile.