Here’s the story: Around 1255, the monk Kichiku, in order to embark upon a pilgrimage, took his leave from Koyasan. He soon arrived at the Kokuzo-do Shrine atop Mt. Asamagatake in present-day Mie Prefecture. He spent the night in deep meditation. Falling in and out of sleep between his prayers, Kichiku had a vivid dream in which he saw himself afloat in a boat on the ocean. Suddenly, while admiring the moon, a dense fog covered everything and blocked out the moonlight. Through the mist, Kichiku heard the forlorn sound of the shakuhachi. The beauty of the music was indescribable. Kichiku awoke from his dream with the sound of the shakuhachi resonating within him. He soon memorized the music he had heard in his dream. The music must certainly be a gift from the Buddha.
The piece became known as “Mukaiji” which roughly translates as “mist-sea-flute.” It is one of the three classic pieces in the shakuhachi repertoire (with “Koku” and “Kyorei”).
Long ago, it seems the flute-playing monk Chokaku had been fascinated by the sound of a wooden bell and attempted with Kyorei (empty bell) to put the sound of the bell to music.
According to legend, the zen monk Kyochiku heard this melody in a dream. The title, “Koku,” translates as the “empty sky” but refers to the original Buddha nature common to all sentient beings.