In February 1989, the Minamioguni Town Board of Education found that there was a mysterious line engraving pattern on this megalith, and then the megaliths in the summit area were nine groups of artificially placed stones. This was confirmed by Prof. Lyle Bolst at State University of New York. after that. It was certified as a prehistoric megalithic cultural site by international academic societies such as the UNESCO Rock Art Society, the American and Canadian Rock Arts Society, and the Japan Petrograph Society.