Elachista sasae is a moth in the Elachistidae family. It was described by Sinev and Sruoga in 1995. It is found in Japan (Hokkaidô, Honsyû) and the Russian Far East (Sakhalin). The length of the forewings is 4–4.7 mm for males and 4.6–5.3 mm for females. The forewings are dark grey-brownish, mottled with light greyish bases of scales. There are three whitish spots. The hindwings are dark grey-brownish. Adults have been recorded on wing in early July and again in September.