Sui-Zen (blowing Zen) is a word for Honkyoku playing where the state of mind is most essential upon playing shakuhachi. Honkyoku, traditional piece passed by Komuso (monk of emptiness) is solo music with few exceptions. No ensemble with other instruments such as Shamisen and Koto was originally practised. Indeed such ensemble was prohibited for Honkyoku playing is considered as a mean to meditate rather than enjoying musical pleasure. This zen aspect of shakuhachi playing occupies unique position in religious music world. Monks blow shakuhachi for their own enlightenment not for entertainment. Yet they blow shakuhachi not for their faith either. This differentiates the Honkyoku playing from religious music.