Koku, or "Bell ringing in the Empty Sky," is one of the three oldest honkyoku (San-Koten). It is said to have been composed after death of the Zen monk Fuke-Zenji, patriarch of the shakuhachi, who in life is supposed to have walked around ringing a small hand-bell. In the legend the monk predicts the day of his own death. When the villagers hear of his death, they open his coffin and find it empty. However, they look to the sky and clearly hear the sound of a bell getting fainter, as if ascending to the clear, blue sky. The music of Koku ("empty sky") supposedly represents this event.