The Japanese squirrel (Sciurus lis) is a tree squirrel in the genus Sciurus endemic to Japan. The Japanese squirrel's range includes the islands of Honshū, Shikoku, and Kyūshū. Recently, populations on south-western Honshū and Shikoku decreased, and those on Kyūshū disappeared. One of the factors affecting the local extinction of this species seems to be forest fragmentation by humans.