Karatsu, Saga
Due to its proximity to mainland Asia, Karatsu has long been known as a stopover to Korea and China.Under ritsuryō, the current city area was part of the Hizen Province. In 1591, on the coast of the northern part of the city (formerly the town of Chinzei), Nagoya Castle was constructed. The following year, it became the location from which the Imjin War was launched by Toyotomi Hideyoshi. In the middle of 1593, Terasawa Hirotaka created the Karatsu domain and began governing it. In 1602, replacing Nagoya Castle, Karatsu Castle was constructed in what is now the heart of Karatsu. The tower of Karatsu Castle was built in 1966 .
Iwasaki Castle (Owari Province)
In an attempt to protect his eastern borders, Oda Nobuhide built Iwasaki Castle in the early 16th century. The castle changed hands in 1529, when Matsudaira Kiyoyasu seized it and made the castle headquarters for the Matsudaira clan. Kiyoyasu's son, Matsudaira Hirotada, moved his residence elsewhere after Kiyoyasu was assassinated in 1535 by one of his retainers, Abe Masatoyo. Niwa Ujikiyo was placed in control of the castle and his descendents continued to rule out of it until Battle of Iwasaki Castle in 1584. The Battle of Iwasaki was part of the larger Battle of Komaki and Nagakute, and during the battle the castle was besieged and taken by the Toyotomi clan's forces led by Ikeda Tsuneoki. The garrison, led by Niwa Ujitsugu, suffered numerous casualties including 300 killed, Ujitsugu's brother Niwa Ujishige being among the dead. The castle was abandoned and destroyed after the Battle of Sekigahara in 1600.