Wave-based imagery and designs, popular among painters of the Rinpa school, are here combined with another favorite image, the folding fan (ōgi), which had a variety of functions in ancient Japan. Its primary use was, of course, to cool its owner in the heat of summer; unfolded, it could also serve as a tray. One type of fan had iron ribs that could be used by warriors as impromptu weapons; others were employed in games or served as props in the performing arts. An important duty of painters in the service of the emperor or shogun was to paint and present fans to the court at the beginning of each year. While used fans were, in general, discarded at the end of summer, they were sometimes kept for their sentimental value and pasted into albums or onto folding screens. A screen ornamented with fans acted as a sort of miniature museum where many works of art could be viewed at once. The fans often appeared against a background of flowing water, a type of imagery that may have evolved from the medieval custom of casting fans into the water to float upon the surface. Screens painted with the fans-and-stream motif, known as “fans afloat” (senmen nagashi), were often installed in shogunal residences and may have derived from a tale about a Muromachi-period shogun who accidentally dropped a fan from a bridge.