Sawayama Castle, Japanese castle in Hikone, Japan

Sawayama Castle is a ruin on Mount Sawayama, about two kilometers from the city of Hikone, offering views over Lake Biwa and the surrounding valleys. The remaining stone walls mark the former building foundations and defenses, distributed across several terrace levels.

Sawayama Castle's origins trace to a fort built by Saho Tokitsuna, sixth son of Sasaki Sadatsuna, in the Kamakura period, with its name appearing in documents of the Kenkyu era (1190-1198). In 1571 Isobe Yukimasa surrendered it to Oda Nobunaga, and Niwa Nagahide took charge. Ishida Mitsunari became lord in 1591 and rebuilt it with a keep; after the Battle of Sekigahara in 1600 it fell, and Ii Naomasa received it. The castle was abandoned in 1606 when Naotsugu moved to Hikone Castle.

The site served as the power base of the Ishida clan and functioned as a strategic outpost, while today only the stone walls show the former layout. Hikers follow a path through the forest that passes by the old defensive lines.

The climb takes around 40 minutes on a wide path that passes through pines and bamboo and becomes steeper in the upper section. Sturdy footwear is necessary because the steps are uneven in places and become slippery after rain.

When the Ii moved to Hikone, Sawayama's keep platform was cut down by about 15 metres and the honmaru was levelled to bare bedrock, so little of the castle's stonework survives. The hilltop today carries a third-order triangulation point marked "Ishigasaki" at 232.57 m. The site belongs to Ryūtan-ji temple below, which allows free entry, and the trailhead is in its grounds.