There are several hundred “yokoana,” or “horizontal holes,” carved into the southern side of Nonodake Hill from Oido to Nakano in Wakuya Town, Miyagi Prefecture. They are the ruins of tombs built from the late 7th to the early 8th centuries.

The site is designated as a historic site by the municipal government. The area including 9 of the caves is arranged into Oido Yokoana History Park and open to the public.

The largest tomb is 9 meters in total length. At the end of the cave is the house-shaped chamber, which has three platforms to place coffins on. The walls of another cave are decorated with chisel carvings and painted red with bengara (iron rust). Pieces of beads made of glass, jade, agate and amber have been excavated, from which it is inferred that those are the tombs of a local ruling family.