After the Kasai clan, the ruler of the southern part of Tohoku region, was destroyed by Toyotomi Hideyoshi’s Oshu Shioki (punishment given to the powerful clans in Tohoku are to prevent their expansion) in 1590, Ichinoseki Castle was given to a Hideyoshi’s retainer, the Kimura clan, and then became a part of the Date domain. In 1604, Date Masamune transferred his uncle, Rusu Masakage, to this castle, but later in the Kanbun era (1661-1672) his 10th son, Munekatsu was feoffed to this castle. Munekatsu, however, was exiled to Tosa province (present-day Kochi Pref.), being accused of causing Date Disturbance in 1671. In 1682, Tamura Tatsuaki, Masamune’s grandson, was transferred from the Iwanuma domain to this castle, and his 10 successors had resided at this castle until the Meiji Restoration in 1868. The ruin of Honmaru (the main castle) called “Senjojiki” is a rectangular land of 100 m by 50 m at the altitude of 90 m above sea level. A ruin of dry moat can be seen on the adjacent hill at the same level as Honmaru, and several other outer compounds were presumably arranged on the terraced land below Honmaru. Koguchi (the main gate) was located in the northeast to Senjojiki. A square land in the southwest is presumed to have been another outer compound such as a watch tower. Now at the side of a small hill in the west of the castle ruins stands Tamura Shrine built by the Tamura clan.
The time of the construction is unknown but it was used as the military base of Oyama clan during the Rebellion of Oyama Yoshimasa (1380-1382). The Oyama clan was an honorable family and its successive family heads were assigned as the governor of Shimotsuke province in the Kamakura period (1192-1333). At the time of the rebellion, Yoshimasa was in the conflict with Utsunomiya Mototsuna for the position of the governor and its territory. He defeated Mototsuna in the battle of Mobara, but he was forced to surrender when Ashikaga Ujimitsu, the Kamakura Kubo (the governor-general of Kamakura) raised a force of soldiers and attacked Washi Castle. Later, Yoshimasa rose in revolt again using branch castles of Chofuku, Shuku, and Iwatubo as the bases, to which Ashikaga Ujimitsu augmented his forces and made an attack on Oyama area. Yoshimasa finally surrendered and the history of Washi Castle ended in the battle. At the present time, the remains of the earthwork with a height of 2 m, the watch tower and the castle entrance are preserved. This is a valuable historic site as the ancient battle field.
The ruins of the medieval Tsunomure Castle are sited on Mt Tsunomure (577m) in Kusu, Oita Prefecture. The castle was built by Mori Tomomichi in the Koan period (1280).
During Japan's period of civil war, Tsunomore held a key position between various states and was fortified by the people of Kusu. In the 14th year of the Tensei period (1586), the castle withstood an attack by Shimazu Yoshihiro.
Today, stone walling some 7m high and 100m long still remains. Moreover, excavation since 1993 has found traces of a watchtower and a gateway dating to the period of Mori Takamasa, who ruled from the castle in the Toyotomi period. There are also remains of another stone gateway and a stone building measuring 10m by 6m. In 2004, Tsunomure Castle Ruin was designated a national historic site.
Shichinohe Castle is said to have been built in the Kamakura period and for a long time was the residence of the Shichinohe Nanbu Clan. In the Edo period, the Nanbu (Morioka) Clan took control of it and placed a magistrate's office there.
The castle is also known as Hakuyo Castle. It is on the edge of a 40m diluvial upland spreading northwest from a junction between the Sakuda and Wada rivers toward an urban district.
The castle remains consist of 7 buildings: the main and secondary ones, the north, west and lower ones, as well as the Horai and square ones, covering a total of about 95,000m2. Each clay wall is original, and the moats, round walls, hillside walls, entrances and warriors' hiding places still remain.
In 1591, the 7 castellans participated in Kunohe Masazane's riot and died. The castle was destroyed in the following year.
Now, as part of the Shichinohe Castle Ruin Protection Plan, excavations are taking place in the north building. In 1996, the main and second buildings were found and 15th-century relics were discovered.