The Kinki, Chugoku and Shikoku regions are located in the western part of the Japanese mainland. This area lacks the Pleistocene volcanic soil except a part of Chugoku Mountains. For this reason, the chronology of the late Paleolithic stone industries has been mainly studied by technology and typology of the fields excavated. However, after the late 1980s, the analysis of volcanic ash that contained the Paleolithic sediments had remarkable development. As a result, the cultural layer between the distant Paleolithic sites is compared by several widespread volcanic ashes such as Aira-Tanzawa (in short AT) as key bed. In this paper, we offered chronological order of the late Paleolithic culture in these regions by comparing cultural layers on the basis of the widespread volcanic ashes, referring to typological analysis of industries. The Sétoüchi technique and Ku industry characterize the late Paleolithic culture in these regions. The Sétoüchi technique is the unique one to produce the Ku type backed knife blunting on only one side, using the particular side-blow flaking technology based on physical characteristics of sanukite stone which is a kind of andesite. However, a hypothesis named the “Sétoüchi concept” was proposed in 2001, and it has been used as a substitute of the “Sétoüchi technique” by a few Japanese researchers. So we point out the mistake of the Sétoüchi concept relying on the fact which yielded stratigraphically two different industries in the Suncheon site.