Tagiades tethys is a species of butterfly of the family Hesperiidae. It is found in eastern Asia, including the Amur region, southern Ussuri, Japan, Taiwan and Korea. The wingspan is about . The larvae feed on various plants, including Quercus mongolica, Dioscorea nipponica, Dioscorea butatas, Dioscorea japonica and Dioscorea japonica var. pseudojaponica.