Joku is the name for matting used for several purposes, including spreading on a desk to put the donated treasures on. As some sumi-ink inscriptions, such as hanadukue-joku (joku for desks for sutras and other Buddhist altar equipments), kyoudai joku (joku for sutra stands) and kouza (seat for lecturers), indicate, joku-s were sometimes made for desks, and sometimes for persons to sit on. Those joku-s use different materials for the filling according to the purposes. Those made to spread on objects, e.g., desks, use the woven mat(s) of soft rush or hemp cloth as the filling material. Colorful Japanese brocade is usually used as the front-side cloth, but there are some cases where fabrics with a twill weave are used instead. Dyed fabrics such as kyoukechi (textiles dyed by carved block resist) are also sometimes used. In many cases, koukechi (textiles dyed by bound resist) plain silk is used for the backside. The shape is usually rectangular, but there are also square and round ones. In Shosoin, there is an octagonal one made to fit the shape of the stand for donated treasures. Among these joku with different shapes, rectangular, square, octagon, and others, there are some with another characteristic; they have a frame made with another piece of cloth around the matting.
This joku is substantially square-shaped, with the brocade front-side and the hemp cloth filling. Originally, it had a frame, as there are traces of it and of the stitches along the four sides of the hemp cloth. The brocade is ukimon no nishiki (lit. brocade with a raised pattern) that features a succession of geometric motifs such as a diamond shape, showing a rather solid structure. It uses light colors with a refreshing atmosphere, which are rare among the brocade textiles made at that time.