Reynoutria japonica is a species in the Reynoutria genus. This name is accepted name for the species in the family Polygonaceae subfamily Polygonoideae, tribe Polygoneae, . . This species is found in Amur, China North-Central, China South-Central, China Southeast, Hainan, Japan, Khabarovsk, Korea, Kuril Is., Manchuria, Nansei-shoto, Primorye, Sakhalin, Taiwan.