Two new species of the family Epitoniidae are described from the continental slope of the Sea of Japan, which is a marginal sea of the northwestern Pacific that has undergone major geographical events since the Lower Pleistocene, and has a rather poor but unique fauna. Papuliscala acus n. sp. was recorded not only in the Sea of Japan but also on several parts of the Pacific coast of Japan, e.g. off Wakayama and Kochi Prefectures, and shows considerable intraspecific variation in size and sculpture. Cirsotrema sugimurai n. sp. is considered to be endemic to the Sea of Japan, and thus one of the survivors of the mass extinction that occurred in the sea during the Last Glacial Maximum, ca. 20,000 years ago.