The Tago's brown frog or simply Tago frog (Rana tagoi) is a species of frog in the family Ranidae endemic to Japan. It is widely distributed within Japan and found on Honshu, Shikoku, and Kyushu, as well as on some outlying islands. There are two subspecies: These might qualify as species. It can also introgres with its sister species, Rana sakuraii. These frogs are found in montane areas close to streams in the leaf-litter, or underneath stones in the streams.