The name of a pure, native Japanese silkworm. During the Edo period through the Meiji, koishimaru was the standard silkworm cultivated in silk farms, but by the 1970s this variety of silkworm had essentially disappeared from commercial silk farms. In 1905, the princess who was later to become Empress Teimei (1884–1951), wife of the Taishō emperor, after paying a visit to Tokyo Sangyō Kōshūjo (now Tokyo University of Agriculture and Technology), brought back some koishimaru silkworms and then in 1914 began to seriously cultivate koishimaru silkworms in the Momiji Mountain Silkworm Farm on the palace grounds. Thereafter, the Showa emperor’s wife, Empress Kōjun (1903–2000), took over the cultivation of koishimaru, and since 1990, the former and present empresses have been cultivating them. The koishimaru produce smaller cocoons than standard modern varieties of silkworms and the amount of silk thread that can be reeled off the koishimaru is essentially half. As, however, it is very close in quality to the Nara period silk, in recent years koishimaru thread cultivated by the Empress has been used for the reproductions of Shōsō-in textiles.