浅水城, Japanese castle in Aomori Prefecture, Japan.

Asamizu Castle is a former Japanese castle in Gonohe, Aomori Prefecture, on a hill on the left bank of the Asamizu River. Its grounds were made up of three enclosures: the main bailey, the second bailey and the third bailey. Across the river stood Asamizu Hall and the Kudo residence. The site is now occupied by a Hachiman shrine.

The castle's founding date is unknown; it is thought to have been held first by the Shinohe clan, who may have taken their name from the place. It later passed to a branch of the Kudo clan after their revolt was defeated in the Tenbun era (1532-1555), and in the Sengoku period it came under the control of the Sannohe Nanbu. A local sign dates its construction to the Eisho years (1504-1520). In 1591, during the Kunohe Masazane rebellion, Moriyoshi of the Minami held off a Kushihiki attack but was killed pursuing the retreating force near Hoshioka. The castle was abandoned in 1631 when Nanbu Toshiyasu, fifth head of the Minami, died at 24.

The castle displays building styles typical of feudal Japan, with stone walls and construction methods adapted to the mountainous terrain of the north. This approach shows how builders in this region integrated natural landscape features into their defensive designs.

Visitors reach the castle ruins via a marked hiking trail that winds through the forested hills of Aomori Prefecture. The terrain requires steady footing, so sturdy shoes and plenty of water are essential for the walk.

If Asamizu Castle was indeed Shinohe Castle, it would line up almost straight along the old Rikuchu road with Hon-Sannohe Castle and Gonohe Castle, and the numbered castles from Ichinohe to Rokunohe follow the same order. About 3 km downstream, on the south bank, stands the Nosawa castle site, now an Inari shrine, built in the Bunmei era by Nanbu Shigeyoshi.