The Toyora Group is one of the in Japan, and was originally named Toyoura Series (or Formation) by Hisakatsu Yabe in 1920. The present name was defined by in 1949. It is the Lower-Upper Jurassic sediments in the East Asian continental margin that distributes in the eastern part of the Shimonoseki, Yamaguchi Prefecture, southwest Japan. The distribution of the Toyora Group extends north and south, and has been separated between north and south districts by the and the that is an active left-lateral strike-slip fault.