Kururi Castle (Kururi-jō) is a Japanese castle located in Kimitsu, southern Chiba Prefecture, Japan. At the end of the Edo period, Kururi Castle was home to a branch of the Kuroda clan, daimyō of Kururi Domain. The castle was also known as U-Jō (Rain Castle ), after a legend that it rained twenty-one times during its construction, or, on average, once every three days. The original Kururi Castle was a mountain-top fortification built during the Muromachi period by Takeda Nobunaga (1401–1477), and was ruled by his descendants, the Mariyatsu Takeda clan, from 1540. With the expansion of the Satomi clan from Awa Province in the Sengoku period, the castle was taken over by Satomi Yoshitaka, who used it as his base of operations against the Hōjō clan, based from Odawara Castle.
The Hōjō attempted to take the castle unsuccessfully on a few occasions, and finally seized it in 1564. They lost it just three years later in 1567, when the Satomi regained control. In 1742, Kururi Domain was reinstated, with Kuroda Naozumi transferred from Numata Domain in Kazusa Province. He rebuilt the fortifications of the old castle, and his descendants continued to rule Kururi Domain until the Meiji Restoration.