The komusō (虚無僧 komusō, hiragana: こむそう; also romanized komusou or komuso)
虚無僧 (komusō) means "priest of nothingness" or "monk of emptiness" were a group of Japanese mendicant monks of the Fuke school of Zen Buddhism who flourished during the Edo period of 1600-1868.
Komusō were characterized by a straw bascinet (a sedge or reed hood named a tengai or tengui) worn on the head, manifesting the absence of specific ego. They were also known for playing solo pieces on the shakuhachi (a type of Japanese bamboo flute). These pieces, called honkyoku ("original pieces"), were played during a meditative practice called suizen, for alms, as a method of attaining enlightenment, and as a healing modality. The Japanese government introduced reforms after the Edo period, abolishing the Fuke sect. Records of the musical repertoire survived, and are being revived in the 21st century.
Fuke Zen came to Japan in the 13th century. Komusō belonged to the Fuke sect of Japanese Zen Buddhism. Fuke Zen comes from the teachings of Linji Yixuan, a Zen teacher from China in the 9th century. Fuke, however, is the Japanese name for Puhua, one of Linji's peers and co-founders of his sect. Puhua would walk around ringing a bell to summon others to enlightenment. In Japan, it was thought the shakuhachi could serve this purpose.
Komusō practiced suizen, which is meditation through the meditative blowing of a shakuhachi, as opposed to zazen, which is meditation through quiet sitting as practiced by most Zen followers. Literally meaning "blowing Zen", suizen pieces (known as honkyoku) prioritized precise breathing control as a function of Zen mindfulness and many were designed to be played in time with a monk's footsteps as he marched long distances on pilgrimage. As Fuke Zen increased in popularity through the Sengoku Period, groups of basket-headed komusō playing for hours on street corners or wandering the roadways on pilgrimages became a common sight.
Travel around Japan was heavily restricted by the Ashikaga shogunate during this rebellious era, but the Fuke sect managed to wrangle a rare exemption from the Shogun, since their spiritual practice demanded a mendicant lifestyle of constant pilgrimage, meditative shakuhachi playing and begging for alms (one famous song reflects this mendicant tradition, "Hi fu mi, hachi gaeshi", "One two three, pass the alms bowl"). They persuaded the Shogun to give them "exclusive rights" to play the instrument and travel about the country as they pleased. In return, some were required to spy for the shogunate, which (quickly recognizing the utility of the ruse) also began dispatching their own spies on secret missions in the disguise of komusō. Ninja and ronin (masterless samurai) were also known to travel in the guise of komusō to avoid official scrutiny of their presence or intentions in a province.
Once this became common knowledge, travelers wearing the komusō outfit became subject to closer inspection, especially in restive and disputed areas. Several particularly difficult honkyoku pieces, e.g., Shika no tone, became well known as "tests": if a suspicious komusō was challenged to play one of the test pieces and was able to reproduce it in the authentic suizen manner, he was accepted as an actual Fuke. If he was unable, or if he refused, he was assumed to be a spy and would likely be immediately arrested.
When the Tokugawa Shogunate came into power over a unified Japan at the beginning of the 17th century, the komusō came under official government criticism for the first time. Because many new komusō had formerly been samurai disenfranchised during the Sengoku (Warring States) period (16th century) who were now lay clergy, the potential for trouble was obvious. Because many of the monks were former samurai, and had become rōnin when their masters were defeated—most likely by the Shogunate and their allies—the komusō (now greater in numbers than ever) were seen as untrustworthy and destabilizing to the new shogunate.