Other than trilobites and ostracods only a few species of arthropods are known from the Palaeozoic of Japan. Here we describe a new bivalved arthropod from the Lower Devonian of central Japan, Norikeya onoi gen. et sp. nov. It shows morphological similarities to both palaeocopine ostracods and phyllocarid malacostracans, but its systematic position remains uncertain. N. onoi lived in warm temperate shallow marine waters. Leperditicopid arthropods that occur in the same formation in central Japan are associated with the Early Devonian leperditicopid biogeographic province of South China, which concurs with the probable palaeogeographic position of central Japan based on other types of evidence.