It is located on the south side of Route 25 and Kouzen village. It is a keyhole-shaped tumulus toward the south of its front. It measures 49 meters in length, but the original length is not clear because its front part has been deformed. It is said that the Prince Shotoku’s beloved horse “Kurokoma” was buried in this tumulus. The excavation conducted by the Ikaruga Town Board of Education suggests that the tumulus was constructed in the second half of the 4th century. It was designated as a Town Historical Site in 1992 together with Choshimaru Tumulus.