Tsuchiura Castle (土浦城 Tsuchiura-jō) is a flatland castle (平城 hirajiro) located in the wetlands along the western shore of Lake Kasumigaura, at the mouth of the Sakuragawa (桜川), in Ibaraki Prefecture.
It is also known as Kijō (亀城, Turtle castle), because in times of severe flooding it looked as if the castle buildings emerged from the water, like a turtle floating on the surface of the sea.
(This map is based on Google Earth. The location may not be completely accurate.)
According to folk tradition the first castle was built in Tsuchiura in the Heian Period. Around 1430, Wakaizumi Saburō (若泉三郎), a vassal of the Oda clan, is supposed to have constructed a fortification on the current location of the castle. Sugenoya Katsusada (菅谷勝貞), another vassal of the Oda who died during the siege of Odawara Castle in 1590, resided there in the Sengoku Period.
After the unification of Japan by Toyotomi Hideyoshi, his son-in-law Yūki Hideyasu (結城秀康; 1574–1607) was installed as new lord. In 1601, the Fujii-Matsudaira (藤井松平家) took over the castle, followed by the Nishio (西尾氏, 1618-1649), the Kutsuki (朽木氏, 1649-1669), the Tsuchiya (土屋氏, 1669-1682), the Ōkōchi (大河内氏, 1682-1687) and again the Tsuchiya until the Meiji Restoration. During Meiji era, the castle was used as a prefectural office. Later on, the site including the main and the second bailey was integrated into Kijō Park.
The castle can easily be reached on foot from Tsuchiura station. I visited it by car and parked near Tsuchiura Municipal Museum (土浦市立博物館 Tsuchiura shiritsu hakubutsukan).
The only remaining original structures are the Taiko-Yagura Gate (太鼓櫓門 Taiko-yaguramon) of the inner bailey (本丸 Honmaru), Kasumi Gate (霞門 Kasumi-mon) and Maekawa Gate which was transferred between the second (二ノ丸 Ni-no-maru) and the outer bailey (三ノ丸 San-no-maru). From 1980 to 1998, the Kōrai Gate (高麗門 Koraimon), the Kasumi Gate (霞門 Kasumimon), the moat as well as the Western Turret (西櫓 Nishi-yagura) were renovated.
Besides, the East Turret (東櫓 Higashi-yagura) and Western Turret were restored. The Eastern Turret is used as a resource centre.
Although the park, nowadays consisting of the inner and the second bailey, appears to be small, it was a massive castle with many layers of moats and earthworks in the Edo Period.