《Kyotaku》 - Kyotaku

...There are various pieces with different titles and contents depending on the school, such as Kinko-ryu "Shinno Kyorei", Saien-ryu/Meian Taizan-ryu "Kyourin", Meian Shinpo-ryu "Shin Kyorin", "Gyo Kyorin", and "Sou Kyorin". According to the legend of the origin of the Fuke shakuhachi, the eccentric monk Fuke Zenji of the Tang Dynasty in China used to preach on the streets while ringing a large bell, and someone who loved the sound of the bell played it on a bamboo pipe to imitate the sound of the bell, and named the piece "Kyoutaku". This is said to be the origin of this series of pieces, but the historical fact is unknown. It is possible that some form of original piece existed in the late Middle Ages or early modern times, and many variants were created through the tradition, but it is difficult to make a conjecture because the current pieces vary greatly between schools and individuals.

*Some of the terminology explanations that mention "Kyodo" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…琴古流《真（しんの）虚霊》，西園流･明暗対山流《虚鈴》，明暗真法流《真（しん）虚鈴》《行（ぎよう）虚鈴》《草（そう）虚鈴》など，流派により曲名と内容の異なるさまざまな曲がある。普化（ふけ）尺八起源伝説によれば，中国唐代の奇僧普化禅師は鐸（たく）(大型の鈴)を振り鳴らしつつ辻説法をするのを常とし，その音を慕った者が竹管で鐸音を模して吹奏し，その曲を《虚鐸》と名づけたのが，これらの一連の曲の起源といわれるが，史実としては不明というほかはない。中世末期ないし近世初期に何らかの形の原曲が存在し，伝承系統により多くのバリアンテを生じた可能性は考えられるが，現行の各曲は流派差･個人差がかなり大きいので，推断は難しい。…

※「《虚鐸》」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報