Honkyoku (本曲) literally means “main/original/true/real music”. The word can refer to a single piece or to the genre as a whole. Honkyoku are the most venerated pieces of shakuhachi music. They were mostly composed by the Komuso monks during the Edo period. Many distinct regional styles of honkyoku developed across Japan though few have survived to this day. Honkyoku are unique in that they are mostly solo pieces with pauses of silence.
Honkyoku are highly nuanced making it virtually impossible to transcribe them to staff notation. Even the Japanese systems of notation for the shakuhachi cannot convey many of the subtleties found in honkyoku. It would be like trying to infer or convey the accent of a regional dialect through written text alone. For this reason the passing down of honkyoku must occur between teacher and student.
It is estimated that there were more than one-hundred Komuso shakuhachi temples across Edo period Japan. However, the Meiji Restoration abolished Buddhism which resulted in the closing or destruction of the temples. The Meiji government soon decided to ban secular shakuhachi playing as well, however, the Kinko Ryu Grandmasters Araki Kodo II (Chikuo) and Yoshida Itcho successfully petitioned the government to allow secular shakuhachi activities to continue. Naturally, secular shakuhachi music became the most popular. Eventually the ban on Buddhism was lifted and the practice of honkyoku could once again continue out in the open, however, interest in it was greatly diminished with a steady decline in Japan up to the present.
Non-Japanese who seek to learn the shakuhachi have been primarily interested in the honkyoku. Outside of Japan we mostly see the propagation of post Edo period honkyoku schools which were created by such master as Jin Nyodo, Watazumi, Nishimura Koku, and Higuchi Taizan (Myoan). One exception to this is the Kinko Ryu which has spread outside of Japan with much success. The Kinko Ryu originates from the former head temple of the Fuke Shu, Ichigetsu-ji.