Hiyama Castle
At the summit of Mt. Kiriyama (145 m) are the ruins of Hiyama Castle, sometimes referred to as Kiriyama-jō. This yamajiro (“mountain castle”) was built in stages during the latter fifteenth century by the Andō clan. Its construction involved leveling large areas of the mountain, then surrounding the peak with fortifications. The castle was demolished in 1620, leaving behind only the flattened land and earthen fortifications.
The site covers more than 1.3 square kilometers and contains the ruins of the inner enclosure (honmaru), a middle enclosure (ninomaru), and the outermost enclosure (sannomaru), elements common in the arrangement of many Japanese castles. Archaeological excavations are underway to unearth the castle’s exact layout and gain more insight into the structures it contained.
The most dramatic episode in the castle’s history came in 1589, during a power struggle between two branches of the Andō clan: the Minato Andō and the Akita, which was the ruling faction at that time. The Minato Andō seized Hiyama Castle and held out for 150 days before the Akita forces breached the defenses. In preparation for the siege, trees on the slopes around the castle were cut down to keep sightlines clear. The slopes were also planted with Siberian onion (Allium ochotense), which made the ground slippery for attackers and provided food for defenders.
At the mountain’s highest point, the inner enclosure offers a sweeping view westward over the city of Noshiro to the Sea of Japan, while the mountains of Shirakami Sanchi rise in the north.