A jinashi natural bore usually has more resistance from nodes and more volume space to fill, a finished jiari bore is smooth and often narrower. As a result, a jinashi plays with a full abdominal air stream, a jiari can play if necessary with a focused throat and mouth air stream. A person with respiratory difficulties could play a jiari shakuhachi, but find it more challenging to fill and control the sounds of a natural wider bore jinashi.
Useful technique to expand the airstream volume cavity for playing extended lengths of large bore jinashi flutes:
jiari (narrow, hard, focused)
jinashi adjustment expansion
jinashi (open, full, flexible)
