I was wondering what this means exactly and how do I know if my shamisen has it and what is the purpose of it? I know ayasugi means zigzag pattern but I have no clue how this term relates to the instrument. Please teach me!
Hi Derik. Here is an Ayasugi Bori. The purpose is to improve the sound of the shamisen. Some think its efficiency is not actually demonstrated but still… It is. Easy to see wether yours has it !
Note, don’t cut your shamisen’s skin (use the hole after removing the sao from the dou) 
Ha, ha, Karl…
LOL thanks very much! So the zigzag pattern on the inside really does help? Do you know how it works? What I mean is: what affect does it have on the sound?