The name Yataki-jo sounds like a puzzle until you realise it just means Yataki castle, and the castle is a ridge in the forested hills behind the old silver town of Omori, in Shimane on the Sea of Japan side. There is no keep, no white walls. What survives is earthworks, terraces cut into the hillside, and the kind of lookout position that makes sense once you stand there and see how many routes it watches. The reason anyone fought over this ground is under it. Iwami Ginzan was among the largest silver mines in the world in the sixteenth century, and the lords of the region, the Ouchi, the Amago and the Mori among them, spent decades taking it from one another.
The riding in these hills is a quiet one. Prefectural roads narrow into one-and-a-half lanes, climb through cedar plantations and cut across steep valleys with a few rice terraces left in the folds. The surface is usually decent but often damp and sprinkled with pine needles, leaves or the odd fallen branch, so stay modest after rain. Moss grows on every north-facing wall, and you will meet more farm trucks than other motorcycles. The nearest proper town is Odachō-oda, about fourteen kilometres away, which has fuel stations, convenience stores and a few places to eat. Higher up, nothing of the sort.
The silver mines and the old street at Omori carry UNESCO listing, and what makes the landscape special is how little scarring there is. Miners worked tunnels rather than open pits and replanted behind them, so the forest has largely taken the area back. Walking up to a castle site you pass over stone steps that are older than most of the villages near them. The trail is rough enough that boots beat riding gear.
Bring a little patience with the weather. The Sea of Japan coast is wet in winter, with heavy snow in the hills some years, and rainy season in June can mean a grey week. Autumn is the best time, when the maples turn and the light slants through the cedars late in the afternoon. Let the day finish on the coast: the harbours along this stretch have good fish at modest prices and are never in a rush.