Practice trills and korokoro with extreme slowness

These techniques are easy to fudge, but they take shape and authority only if they are practiced slowly enough that they can be rendered perfectly. That is to say that each note of the sequence is clearly blown.

At first, your renditions might seem painfully slow. If you record your slow rendition, you will notice that even at a slow pace, the authority of the note-making is sufficient to carry the meaning of the sequence. In other words, accuracy is much more important than speed. One does not need to consciously try to speed up these phrasings. If you play them accurately and slowly, you will automatically increase their speed without losing good form. If good form disappears with speed, then you can slow your practice down once again, to regain good form

The shakuhachi path
Shakuhachi lessons