The Seishiden Ruins are situated in Kawaradake and San no Take mountains. In the latter half of the Heian period (794-1185), there is a document remaining at Komiya Shrine showing that a sacred mirror that was enshrined at Usa Shrine in Oita Prefecture. It is thought that the place where this sacred mirror was cast was at Saidosho Ruins. Located nearby is the tunnel called Mabu where copper was mined. This deep place, connected to Komiya Shrine, is called Kanmabu also.The roof (pictured) at the front shrine is a shingled roof. The shrine itself has an apperance of a semi-detached house. In the middle of the dirt floor is an area that was used as a smithing area. At the back of this building there is a small shrine and the base of 3 granite pillars. It is believed that the sacred mirror completed here was dedicated at these 3 pillars. In 1956, the Seishin Ruins were designated a historic cultural asset of Fukuoka Prefecure.