S P O T ／ SPOT-033

Masuda no Iwafune (Masuda's Rock Boat)

益田岩船ますだのいわふね

On a hilltop in Kashihara City, on the southern edge of the Asuka Valley, sits an 800-ton granite boulder so large that its own geology seems insufficient explanation for its presence. It measures 11 meters by 8 meters at the base and stands approximately 4.7 meters tall; its upper surface has been carved with two circular pits each about 1 meter in diameter and 1 meter deep, connected by a channel, alongside a network of surface grooves whose function no scholar has satisfactorily explained. The boulder's name — "Masuda's Rock Boat" — derives from a tradition that enormous stones arrived in Asuka from the sky, delivered by forces that ordinary earthbound labor could not account for. The carving is clearly the work of human hands, probably Imperial-era, but the original purpose of the two deep pits remains entirely open: tomb preparation, astronomical alignment device, water ritual basin, and ritual mirror stand have all been proposed, and none has prevailed. Active archaeological research continues.