Japan is home to the kofun — vast, keyhole-shaped burial mounds as historically significant as the Egyptian pyramids, yet little known outside the country. Led by Italian archaeologist Daniele Petrella, an international team undertakes the first major Western-led study of these monumental tombs, excavating the Tobiotsuka Kofun and exploring sites across Japan. The film reveals the historical and social importance of these extraordinary monuments and the secrets they still hold.