Kannonji Temple, now a hiking trail, is the historical site where Hideyoshi and Mitsunari Ishida met and is located at the foot of Yokoyama Castle. The date of construction of Yokoyama Castle is unknown, but it once served as a branch castle of the Kyogoku clan. It was attacked down by Asai Ryomasa in 1517, after which Asai Nagamasa, lord of Kotani Castle, rebuilt the castle in 1564 and placed Onogi Shigetoshi as its general. In the Battle of Anegawa, Oda and Tokugawa forces attacked Yokoyama Castle and appointed Hideyoshi Kinoshita Fujikichiro as the castle's representative. Then, in 1573, Nobunaga invaded Kotani Castle and destroyed the Asai clan. Today, the ruins of Yokoyama Castle include the ruins of the main castle, an empty moat, and earthen mounds, and the ruins of related fortifications have also been confirmed in the surrounding area.