Fu, wind or air, is the fourth of the Godai, the five elements of Japanese esoteric Buddhism, the element of movement, breath and expansion, the moving air, associated with growth, freedom, and the mind's liberty and openness, and with things that spread and travel. In the gorinto, the five-ring stone pagoda, wind is the crescent or half-moon form set above the pyramid of fire, near the top of the monument, expressing the element's lightness and its nearness to the formless void above.
The five elements reached Japan through the esoteric Buddhist transmission from India, mediated by China, and were systematised in the Shingon school of Kukai. Miyamoto Musashi's Book of Five Rings names its wind chapter for the study of other schools and traditions, the wider air beyond one's own. The Godai are an ancient and continuous part of Japanese Buddhist and martial culture, and wind's attributes of movement and expansion belong to that inherited elemental scheme rather than to any modern system.